What is pycnogenol

Pycnogenol is a patented, proprietary powder extract made exclusively from French maritime pine (Pinus pinaster Aiton) bark by Horphag Research (Geneva, Switzerland) ¹⁾. Pycnogenol is a standardized extract from the bark of the French maritime pine consists of a concentrate of polyphenols. A pharmacokinetic study with volunteers ingesting Pycnogenol revealed that catechin, caffeic acid, ferulic acid, taxifolin and the metabolite M1 (δ-(3,4-dihydroxy-phenyl)-γ-valerolactone) were detectable in a nanomolar range in plasma ²⁾. Moreover, about 65–75 % of the Pycnogenol extract are procyanidins that consist of catechin and epicatechin subunits of varying chain lengths ³⁾, besides taxifolin, catechin, and phenol acids ⁴⁾. The active ingredients in maritime pine can also be extracted from other sources, including peanut skin, grape seed, and witch hazel bark. Procyanidin is a powerful antioxidant also found in food such as grapes, berries, pomegranates, red wine and various nuts. Maritime pine bark extract, pycnogenol, is commonly used orally to treat and prevent diabetes, diabetes-related health issues, and problems of the heart and blood vessels among many other uses. Some people use skin creams that contain maritime pine bark extract as “anti-aging” products. Pycnogenol is also applied to the skin to treat foot ulcers in people with diabetes, hemorrhoids, and mouth ulcers caused by chemotherapy. There is limited scientific research to support most of these uses.

French maritime pine bark extract is a complex mixture of polyphenolic compounds ⁵⁾. A catechin metabolite (M1) produced by human intestinal bacteria was found in the plasma samples. Subsequent investigations showed that M1 exerted various anti-inflammatory effects in vitro such as the inhibition of the activity of the matrix metalloproteinases MMP-1, −2 and −9, decrease of the release of MMP-9 from human monocytes or inhibition of the expression of the inducible NO synthase (iNOS) in RAW 264.7 macrophages ⁶⁾. In other in vitro experiments using the whole extract a decrease of IL1B mRNA synthesis in RAW 264.7 cells was reported ⁷⁾ as well as inhibitory effects on the expression of COX-2, IL-8 and iNOS in human chondrocytes and fibroblasts ⁸⁾. However, since not all components of the French maritime pine extract are bioavailable and other bioactive molecules such as M1 are generated in vivo, it is not clear whether experiments using the whole extract would be indicative for cellular effects that actually occur in vivo.

Clinical studies indicate that pycnogenol is effective in the treatment of chronic venous insufficiency and retinal micro-hemorrhages ⁹⁾. Pycnogenol protects against oxidative stress in several cell systems by doubling the intracellular synthesis of anti-oxidative enzymes and by acting as a potent scavenger of free radicals. Other anti-oxidant effects involve a role in the regeneration and protection of vitamin C and E. Anti-inflammatory activity has been demonstrated in vitro and in vivo in animals. Protection against UV-radiation-induced erythema was found in a clinical study following oral intake of pycnogenol ¹⁰⁾. In asthma patients symptom scores and circulating leukotrienes are reduced and lung function is improved ¹¹⁾. Immunomodulation has been observed in both animal models as well as in patients with Lupus erythematosus. Pycnogenol antagonizes the vasoconstriction caused by epinephrine and norepinephrine by increasing the activity of endothelial nitric oxide synthase. Dilation of the small blood vessels has been observed in patients with cardiovascular disease, whereas in smokers, pycnogenol prevents smoking-induced platelet aggregation and reduces the concentration of thromboxane ¹²⁾. The ability to inhibit angiotensin-converting enzyme is associated with a mild antihypertensive effect ¹³⁾. Pycnogenol relieves premenstrual symptoms, including abdominal pain and this action may be associated with the spasmolytic action of some phenolic acids ¹⁴⁾. An improvement in cognitive function has been observed in controlled animal experiments and these findings support anecdotal reports of improvement in ADHD patients taking pycnogenol supplements ¹⁵⁾.

Chemical identification studies showed that pycnogenol is primarily composed of procyanidins and phenolic acids. Procyanidins are biopolymers of catechin and epicatechin subunits which are recognized as important constituents in human nutrition. Pycnogenol contains a wide variety of procyanidins that range from the monomeric catechin and taxifolin to oligomers with 7 or more flavonoid subunits ¹⁶⁾. The phenolic acids are derivatives of benzoic and cinnamic acids. The ferulic acid and taxifolin components are rapidly absorbed and excreted as glucuronides or sulphates in men, whereas procyanidins are absorbed slowly and metabolized to valerolactones which are excreted as glucuronides. As all of these constituents of Pycnogenol and its metabolites exhibit anti-inflammatory actions, the progressing appearance of the diverse active substances provides a long-lasting pain relief, so that patients feel less pain, also during the night ¹⁷⁾. Pycnogenol has low acute and chronic toxicity with mild unwanted effects occurring in a small percentage of patients following oral administration.

Pine bark extract vs Pycnogenol

French maritime pine (Pinus pinaster Aiton) bark extract is a complex mixture of bioflavonoids, with oligometric proanthocyanidins as the major constituents. Oligometric proanthocyanidins are dimers or oligomers of catechin, epicatechin, and their gallic acid esters. The major oligometric proanthocyanidins in maritime pine bark are proanthocyanidin B1 (epicatechin-(4β→8)-catechin), catechin, and epicatechin ¹⁸⁾.

Pycnogenol is a patented, proprietary powder extract made exclusively from French maritime pine (Pinus pinaster Aiton) bark by Horphag Research (Geneva, Switzerland) ¹⁹⁾. Pycnogenol is a standardized extract from the bark of the French maritime pine consists of a concentrate of polyphenols. A pharmacokinetic study with volunteers ingesting Pycnogenol revealed that catechin, caffeic acid, ferulic acid, taxifolin and the metabolite M1 (δ-(3,4-dihydroxy-phenyl)-γ-valerolactone) were detectable in a nanomolar range in plasma ²⁰⁾. Moreover, about 65–75 % of the Pycnogenol extract are procyanidins that consist of catechin and epicatechin subunits of varying chain lengths ²¹⁾, besides taxifolin, catechin, and phenol acids ²²⁾. The active ingredients in maritime pine can also be extracted from other sources, including peanut skin, grape seed, and witch hazel bark. Procyanidin is a powerful antioxidant also found in food such as grapes, berries, pomegranates, red wine and various nuts.

Pycnogenol benefits

Possibly effective for:

• Allergies: Some research shows that taking a standardized extract of maritime pine bark before allergy season begins reduces allergy symptoms in people with birch allergies.
• Asthma: Taking a standardized extract of maritime pine bark daily, along with asthma medications, seems to decrease asthma symptoms and the need for rescue inhalers in children and adults with asthma.
• Athletic performance: Young people (age 20-35 years) seem to be able to exercise on a treadmill for a longer time after taking a standardized extract of maritime pine bark daily for about a month. Also, athletes training for a physical fitness test or a triathalon seem to perform better in the tests and competitions when they take this extract daily for 8 weeks while training compared to only training.
• Circulation problems: Taking a standardized extract of maritime pine bark by mouth seems to reduce leg pain and heaviness, as well as fluid retention, in people with circulation problems. Some people also use horse chestnut seed extract to treat this condition, but using the extract alone appears to be more effective.
• Improving mental function: Research suggests that taking a standardized extract of maritime pine bark by mouth for 3 months improves mental function and memory in both young adults and the elderly.
• Disease of the retina in the eye: Taking a standardized extract of maritime pine bark by mouth for 2 months seems to slow or prevent further worsening of retinal disease caused by diabetes, atherosclerosis, or other diseases. It also seems to improve eyesight..

Insufficient evidence to rate effectiveness for:

• Attention deficit-hyperactivity disorder (ADHD). Taking a standardized extract of maritime pine bark by mouth does not seem to help ADHD symptoms in adults. However, taking it by mouth for one month appears to improve symptoms in children.
• Common cold. Taking a standardized extract of maritime pine bark by mouth twice daily starting at the beginning of a cold seems to reduce the number of days with a cold and the number of lost working days. It also seems to reduce the amount of over-the-counter cold products needed to manage symptoms.
• Clogged arteries (coronary artery disease). There is some evidence that taking a standardized extract of maritime pine bark three times daily for 4 weeks might help improve some complications associated with clogged arteries.
• Blood clots in deep veins (deep vein thrombosis, DVT). There is some evidence that taking a specific combination product containing maritime pine might help to prevent DVT during long-haul plane flights. The product combines a blend of standardized maritime pine bark extract plus nattokinase. Two capsules are taken 2 hours before the flight and then again 6 hours later. Also, taking the standardized maritime pine bark extract before a flight, 6 hours after the flight, and the following day appears to reduce the risk of blood clots forming in the veins during long flights. In addition, taking the extract for one year eems to reduce the risk of post-thrombotic syndrome. This condition can develop in people who already experienced a blood clot.
• Dental plaque. Early research suggests that chewing at least 6 pieces of gum with added extract from maritime pine bark for 14 days reduces bleeding and prevents increased plaque.
• Diabetes. Early evidence suggests that taking a standardized extract of maritime pine bark daily for 3-12 weeks slightly decreases blood sugar in people with diabetes.
• Foot ulcers due to diabetes. Early research suggests that taking maritime pine bark extract by mouth and applying it to the skin helps heal foot ulcers related to diabetes.
• Circulation problems in diabetes. Early research shows that taking standardized maritime pine bark extract three times daily for 4 weeks improves circulation and symptoms in people with diabetes.
• Swelling (edema). Early research suggests that taking standardized extract of maritime pine bark before a flight, 6 hours after the flight, and once the next day reduces ankle swelling.
• Erectile dysfunction (ED). Early research suggests that standardized maritime pine bark extract, used alone or in combination with L-arginine, might improve sexual function in men with ED. It seems to take up to 3 months of treatment for significant improvement.
• Heart failure. Early research suggests that taking a specific combination product containing standardized maritime pine bark and coenzyme Q10 for 12 weeks improves some symptoms of heart failure.
• Hemorrhoids. Early research suggests that taking standardized extract of maritime pine bark by mouth, alone or in combination with a cream containing this same extract, improves quality of life and symptoms of hemorrhoids.
• High cholesterol. A standardized extract of maritime pine bark seems to lower “bad cholesterol” (low-density lipoprotein (LDL) cholesterol) in people with high cholesterol. However, the extract doesn’t seem to improve cholesterol levels in people with other conditions such as high blood pressure, type 2 diabetes, erectile dysfunction, and others.
• High blood pressure. One standardized extract of maritime pine bark (Pycnogenol, Horphag Research) seems to lower systolic blood pressure (the top number in a blood pressure reading) but does not significantly lower diastolic blood pressure (the bottom number). This extract might also help lower blood pressure in some patients already treated with the blood pressure-lowering drug ramipril. However, other maritime pine bark extract (Toyo-FVG, Toyo Bio-Pharma) does not appear to lower blood pressure in obese people with slightly high blood pressure.
• Leg cramps. There is some evidence that taking a standardized extract of maritime pine bark by mouth daily might decrease leg cramps.
• Menopausal symptoms. Early research shows that taking a standardized extract of maritime pine bark by mouth decreases menopausal symptoms, including tiredness, headache, depression and anxiety, and hot flashes.
• Metabolic syndrome. Early research suggests that taking a standardized extract of maritime pine bark by mouth three times dialy for 6 months lowers triglycerides, blood sugar levels, and blood pressure, and increases high-density lipoprotein (“good” or HDL) cholesterol in people with metabolic syndrome.
• Oral mucositis. Applying solution containing a standardized extract of maritime pine bark inside the mouth for one week seems to help heal mouth ulcers in children and adolescents undergoing chemotherapy treatment.
• Osteoarthritis. There is mixed evidence about the effectiveness of maritime pine for osteoarthritis. Taking a standardized extract of maritime pine bark by mouth might reduce overall symptoms, but it does not seem to reduce pain or improve the ability to perform daily tasks.
• Pain in late pregnancy. Early research suggests that taking a standardized extract of maritime pine by mouth daily during the last 3 months of pregnancy reduces lower back pain, hip joint pain, pelvic pain, and pain due to varicose veins or calf cramps.
• Pelvic pain in women. There is early evidence that taking a standardized extract of maritime pine bark by mouth might help reduce pelvic pain in women with endometriosis or severe menstrual cramps.
• Problems with sexual function. Early research suggests that taking a combination product containing a standardized extract of maritime pine bark, L-arginine, L-citrulline, and rose hip extract daily for 8 weeks can help improve sexual function in women.
• Improving symptoms of lupus (SLE). Early research suggests that taking a standardized extract of maritime pine bark by mouth reduces symptoms of SLE in some patients.
• Ringing in the ears (tinnitus). Early research suggests that taking a standardized extract of maritime pine bark by mouth reduces ringing in the ears.
• Stroke prevention.
• Muscle soreness.
• Other conditions.

More evidence is needed to rate pycnogenol for these uses.

Anti-inflammatory activity

The constituents of Pycnogenol act in concert, as all of its phenolic compounds are scavengers of free radicals and exhibit a range of anti-inflammatory actions, as documented for ferulic acid, caffeic acid, catechin, and taxifolin ²³⁾.

The metabolites, formed by ring fission of catechin units by microbiota, possess also remarkable anti-inflammatory activity. The procyanidin metabolite M1 showed in vitro a 100% higher activity than hydrocortisone ²⁴⁾. These initial in vitro effects could be proven in ex vivo experiments.

Plasma collected from volunteers subsequent to consumption of Pycnogenol, inhibited the activity of cyclooxygenases 1 and 2, as well as the activation of the inflammation “master switch” nuclear factor kappa B (NFκB) ²⁵⁾.

Human pharmacokinetic investigations indicated that the metabolite M1 is enriched in blood cells by active transport mechanisms, so that anti-inflammatory activity of blood is most probably 30 times higher than measured in plasma ²⁶⁾.

Furthermore, the active metabolite M1, ferulic acid, and caffeic acid are present in the synovial fluid, thus acting directly on the source of inflammation in case of synovitis ²⁷⁾.

Protection of articular cartilage

The progression of osteoarthritis is connected with a blockage of synthesis of proteoglycan components and type 2 collagen by inflammatory cytokines and tumor necrosis factor alpha ²⁸⁾. Furthermore, cartilage degrading proteolytic enzymes such as matrix metalloproteinases (MMPs) are liberated as MMP-1, MMP-2, and MMP-13 ²⁹⁾. The metabolite M1 formed from the procyanidins of Pycnogenol inhibited the activity of MMP-1, MMP-2, and MMP-9 in vitro and blocked the release of MMP-9 from activated monocytes ³⁰⁾. The oral intake of Pycnogenol downregulated the gene expression of various cartilage degradation markers in the patients’ chondrocytes, the decrease of MMP3, MMP13 and the pro-inflammatory cytokine IL1B were statistically significant. Additionally, protein concentrations of ADAMTS-5 in serum were reduced significantly after three weeks intake of the pine bark extract ³¹⁾. These chondroprotective effects were confirmed in ex vivo experiments. Plasma, taken from human volunteers following intake of Pycnogenol, inhibits the release of NFκB and MMP-9 from activated monocytes. The inhibition of the master switch of inflammation NFκB, acting together with inflammatory cytokines, reduces considerably the inflammatory process connected to osteoarthritis. Analysis of synovial fluid from osteoarthritis patients revealed the presence of ferulic acid, caffeic acid, taxifolin, catechin, and the metabolite M1 in serum, blood cells, and synovial fluid ³²⁾. The anti-inflammatory substances ferulic acid, caffeic acid, and the active metabolite M1 were enriched in the synovial fluid relative to serum. So, the chondroprotective and anti-inflammatory action take place locally in the synovia.

Pycnogenol acts like a sustained-release formulation by its combination of fast absorbed phenolic compounds and slowly metabolized procyanidins. Its constituent ferulic acid and the metabolite M1 are enriched in synovial fluid and contribute to local anti-inflammatory action.

Pycnogenol as an anti-inflammatory and chondroprotective add-on supplement provided long-lasting positive effects such as enhanced physical mobility and pain relief for patients with mild osteoarthritis. The use of NSAIDs could be significantly reduced, thus diminishing unwanted effects of NSAIDs. Studies involving more patients are needed to confirm the beneficial actions of Pycnogenol on an even broader basis.

The reduced anti-inflammatory activity in osteoarthritis with Pycnogenol is reflected in a decrease of C-reactive protein levels in osteoarthritis patients by 70%, with plasma-free radicals simultaneously scavenged by 30% ³³⁾.

The cooperation of the diverse anti-inflammatory effects of Pycnogenol in plasma and synovial fluid results in reduction of pain and increased mobility.

Three identically designed clinical trials investigating the role of Pycnogenol in osteoarthritis treatment have been published to date ³⁴⁾, ³⁵⁾, ³⁶⁾.

All studies were randomized, double blind, and placebo controlled. Middle-aged patients (48–54 years) suffering from mild osteoarthritis, stage I or II, verified by X-ray, were treated either with 3 × 50 mg Pycnogenol daily or placebo, added to existing therapy with NSAIDs. Success of the add-on supplementation was objectivated by the Western Ontario McMasters University (WOMAC) questionnaire for osteoarthritis during a period of 3 months. Results are summarized in Table 1. It has to be emphasized that patients were allowed to use their NSAIDs as concomitant medication when needed.

The first, small-scale study (n = 35) showed a clear reduction of scores for pain, functionality, and total WOMAC score, dependent on duration of treatment ³⁷⁾. After 3 months, significant differences to placebo were observed, symptoms were reduced by 43%, 35%, 52%, and 49% for pain, stiffness, physical function, and total WOMAC score, respectively.

In the second study, involving 100 patients, the pain score improved significantly with time compared to baseline ³⁸⁾. In this study, a considerable placebo effect was observed for pain, daily activity scores, and overall WOMAC scores, and although improvement relative to baseline was highly significant, the difference to placebo did not reach significance level in any case. Only scores for stiffness improved significantly both to baseline and versus placebo after 2 and 3 months, while placebo had no effect.

A total of 156 patients were included in the third study ³⁹⁾. Symptom scores dropped significantly: pain by 45%, stiffness by 47%, physical function by 43%, and overall WOMAC score by 44%. The decrease under placebo was not significant. A more detailed analysis of the WOMAC scores of the third study revealed a significant reduction of nocturnal pain and pain during troublesome stair climbing, particularly relevant for the quality of life of osteoarthritis patients ⁴⁰⁾.

Also, for joint stiffness during the day, only minor changes were observed with placebo, while Pycnogenol improved stiffness remarkably.

An example for an enhanced physical function refers to the onerous rising from sitting: with Pycnogenol the score dropped clearly from initial 3.1 to 0.8, with placebo the score remained nearly unchanged (3.0 to 3.1).

The improvement of osteoarthritis was impressively objectivated by performance of patients on a treadmill. Patients in the Pycnogenol group could increase their walking distance after 3 months from 68 to 198 m, whereas placebo expanded walking distance from 65 m just to 88 m ⁴¹⁾.

These positive effects related to relief from daily pain, stiffness, and physical function had of course a great influence on the well-being of the patients in the Pycnogenol group. As the negative impact of osteoarthritis on daily activities subsided, the emotional status of patients shifted significantly from irritability, frustration, depression, and insomnia to better well-being ⁴²⁾. The sum of negative emotional scores dropped from 31.4 to 11.5, whereas placebo had a nonsignificant effect (28.4 to 24.1). Thus, quality of life was definitely improved in the Pycnogenol group.

Use of NSAIDs was significantly reduced in all three studies in the Pycnogenol group, in contrast to a slight increase of intake of NSAIDs in the placebo group. A more precise evaluation of NSAID use was performed in the third study ⁴³⁾.

Intake of Pycnogenol allowed patients to decrease intake of NSAID medication by 58% according to their diaries ⁴⁴⁾. Correspondingly, gastrointestinal complications decreased by 63% as well as days spent in hospital (60%). Values under placebo decreased by only 1% (reduction of use of NSAIDs) and 3% (reduction of hospital admissions and gastrointestinal problems).

Together, the three clinical studies demonstrate an improvement of symptoms of mild osteoarthritis under Pycnogenol, despite the reduced intake of NSAIDs. No unwanted effects of Pycnogenol were reported in the three studies. This is in line with the safety profile of Pycnogenol. Unwanted effects such as headache, dizziness, nausea, sleepiness, skin irritation, and gastric troubles were mild with a rate of 1.9% in clinical trials involving 7000 patients ⁴⁵⁾.

Table 1. Overview of 3 clinical trials demonstrating efficacy of pycnogenol for arthritis

Pycnogenol and ADHD

Attention-deficit and hyperactivity disorder (ADHD) is a complex and multifactorial disorder, influenced by both genetics and the environment. Its exact pathophysiology remains, however, unclear. Dopaminergic dysfunction is involved, but also associations with immune and oxidant-antioxidant imbalances exist ⁵⁰⁾. Various studies demonstrated, for example, increased levels of plasma malondialdehyde (MDA) and exhalant ethane (oxidative stress markers) and decreased activity of antioxidant enzymes such as glutathione peroxidase (GPX) and catalase (CAT) ⁵¹⁾. ADHD has also been hypothesized to be a hypersensitivity disorder, with a disrupted immune regulation contributing to its cause ⁵²⁾; i.e. ADHD has comorbidity with both Th1- and Th2-mediated disorders and several related genes have immune functions ⁵³⁾. Ceylan et al. ⁵⁴⁾ observed increased levels of adenosine deaminase, a marker of cellular immunity, and of the oxidative enzymes xanthine oxidase and nitric oxide synthase, and decreased levels of the antioxidant enzymes glutathione-S-transferase and paraoxonase-1. These results indicate the involvement of oxidative changes and cellular immunity in ADHD ⁵⁵⁾.

Methylphenidate, the first-choice medication for ADHD, is a central nervous system stimulant. It increases attentiveness and reduces hyperactivity and impulsivity by inhibition of dopamine reuptake in the striatum, without triggering its release. methylphenidate is prescribed for chronic use to a large proportion of ADHD patients, but is linked to possible publication bias in reported efficacy ⁵⁶⁾. In addition, parents are often disinclined to use methylphenidate due to its negative publicity and its frequent side effects, including serious side effects like arrhythmia, and, subsequently, nonadherence to therapy is high ⁵⁷⁾. A recent review reports adverse effects, like insomnia and decreased appetite, in about 25% of patients using methylphenidate ⁵⁸⁾. Other therapeutic options are therefore warranted, at least for a subgroup of patients ⁵⁹⁾.

In one previous trial on twenty-four adults (24 to 53 years old) with attention-deficit/hyperactivity disorder (ADHD), the effect of Pycnogenol was compared to methylphenidate and placebo. However, neither methylphenidate nor Pycnogenol outperformed placebo, possibly due to the short treatment period of 3 weeks ⁶⁰⁾. Further research is needed to investigate its efficacy, mechanism of action and value, especially compared to methylphenidate treatment. For example, dietary polyphenols and their metabolites exert prebiotic-like effects, stimulating the growth of intestinal microbiota, which play a fundamental role in immunity ⁶¹⁾. Also the Pycnogenol dosage is based upon this previous clinical trial, using 1 mg/kg body weight ⁶²⁾.

Pycnogenol effects on human skin

A number of studies provide compelling evidence that oral supplementation with Pycnogenol protects human skin against UV radiation. Accordingly, in a study on 21 fair-skinned volunteers, Saliou et al. ⁶³⁾ demonstrated that oral ingestion of 1.10 mg or 1.66 mg/kg body weight/day Pycnogenol is effective in reducing UV-induced erythema. In this study, the UV protective effect of Pycnogenol was found to be dose dependent, to develop after 4-8 weeks of oral intake and to almost double the individual minimal erythema dose which was determined prior to Pycnogenol intake. The strength of this study is the intraindividual comparison of minimal erythema doses before, during and after Pycnogenol intake as well as the observed dose dependency of minimal erythema dose increases. Weaknesses of the study include the lack of a placebo treatment, e.g. in a crossover design or a comparator group. Although the study has been conducted during winter/spring time, the study has not been controlled for the seasonal increase in exogenous antioxidants in the regular diet which is often observed during summer and autumn ⁶⁴⁾. Also, it should be noted that solar radiation-induced erythema responses mainly result from the formation of DNA photoproducts such as cyclobutane pyrimidine dimers in human skin, which can be reduced by antioxidants only to some extent. In other words, photoprotection by Pycnogenol might be even greater than observed here, if other biological end points, which more strongly depend on UV radiation-induced oxidative damage, would have been studied. Accordingly, oral ingestion of the carotenoid lycopene was previously shown to only moderately reduce solar UV radiation-induced erythema by 37% ⁶⁵⁾, whereas long-wave UVA radiation-induced gene transcription, which strictly depends on the generation of reactive oxygen species in human skin, was almost completely inhibited ⁶⁶⁾. It should also be noted that in vivo animal studies show that oral ingestion by mice significantly reduces the number and growth rate of skin tumors which were induced either by chronic UVB irradiation or by a combination of UVB radiation with topical treatment of skin with the polyaromatic hydrocarbon 7,12-dimethylbenzanthracene ⁶⁷⁾. As UVB- as well as polyaromatic hydrocarbon-mediated skin carcinogeneses both critically involve activation of the aryl hydrocarbon receptor ⁶⁸⁾ and since flavonoids such as catechin and epicatechin, which are a main constituent of Pycnogenol, have been shown to inhibit aryl hydrocarbon receptor activation ⁶⁹⁾, it is tempting to speculate that oral ingestion of Pycnogenol may help to suppress environmentally induced aryl hydrocarbon receptor activation in skin cells.

Pine bark extract and photoaged facial skin

Furumura et al. ⁷⁰⁾ enrolled 112 healthy women younger than 60 years with age spots, mostly diagnosed as solar lentigines, and multiple symptoms of photodamaged skin, including mottled pigmentation, roughness (including dry flaky skin), wrinkles, and swelling. All women enrolled in this study had mild to moderate facial photodamage graded on the Glogau scale between II and III and Fitzpatrick skin phototypes III to IV. After approval by the institutional ethics committee of Fukuoka University, which adheres to the principles of the Declaration of Helsinki, informed consent was obtained from all participants in the study. None of the subjects took topical/systemic retinoids, health food supplements, oral medications such as hormone replacement therapy, or topical medications, or were pregnant 4 weeks prior to enrolling in this study.

Twenty-four women were enrolled in an open-label, high-dose pine bark extract (Flavangenol®) trial and were treated with 100 mg/day pine bark extract (Flavangenol®) for 12 weeks, while a further 88 women were enrolled in part 1 of a separate low-dose trial and treated with pine bark extract (Flavangenol®) 40 mg/day for a total of 24 weeks in an open-label, randomized, parallel-group comparative fashion. Group 1 participants were asked to take pine bark extract (Flavangenol®) 40 mg/day once daily, and to use a cleanser and sunscreen for 24 weeks throughout part 1 of the study. Group 2 participants were merely placed under observation without taking pine bark extract (Flavangenol®) for the first 12 weeks before starting oral treatment with pine bark extract (Flavangenol®) 40 mg/day once daily for the next 12 weeks, and were instructed to use a cleanser and sunscreen for 24 weeks throughout part 1 of the study.

Furumura et al. ⁷¹⁾ examined the efficacy of pine bark extract in the treatment of photodamaged facial skin, and significant improvement was suggested from multiple dermatological score assessments during this study.

A subject questionnaire concerning subjective facial symptoms demonstrated that a relatively large number of subjects felt that the roughness of their facial skin had improved in the high-dose trial. Although improvement in age spots was only recognized by a relatively small number of subjects in the high-dose trial [100 mg/day pine bark extract (Flavangenol®)], detailed evaluation of digital images revealed that 71% of participants had improvement of their age spots, albeit to a varying extent. In part 1 of the low-dose trial [40 mg/day pine bark extract (Flavangenol®)], there was significant improvement in scores for solar lentigines, mottled pigmentation, skin roughness, and swelling only when subjects were on treatment with pine bark extract. Further, subjects treated with pine bark extract had significantly lower scores for solar lentigines and skin roughness when compared with the untreated patients. Therefore, we consider that both the high-dose and low-dose arms in this study demonstrate a similar trend of improvement in symptoms of photodamaged facial skin. Further significant improvements were seen during the long-term 18-month study (part 2 of the low-dose trial) in almost every photoaging score. This improvement was maintained and enhanced by continuous administration of pine bark extract over a long period. Finally, 72% of the subjects receiving pine bark extract for 12 weeks (group 2) showed improvement versus 87% of those receiving pine bark extract for 24 weeks (group 1). All subjects who completed treatment with pine bark extract for 15–18 months showed improvement in symptoms. In line with the score assessment results, objective biophysical measurements demonstrated a significant gradual decrease in average melanin index during treatment with pine bark extract in both trials.

In an earlier study of treatment of photoaged skin with oral polyphenols ⁷²⁾, a popular polyphenol-rich green tea extract containing (−)-epigallocatechin gallate (EGCG) was used. Although facial photoaging scores improved on treatment with the green tea extract for the first 12 months, there was no significant antiphotoaging effect after 24 months of treatment. In contrast, gradual improvement of photoaging scores even at 18 months was confirmed in their pine bark extract trial. Demographic diversity in subject age and race might account for the different results seen in these two studies. The mean age of the subjects in the previous study was around 12 years older than in Furumura et al. ⁷³⁾ study, so a less favorable outcome would be expected because of the exponential decline of intrinsic antioxidative potency in the elderly. Furumura et al. ⁷⁴⁾ findings in Japanese women might be positively biased by a racial difference, ie, age spots in East Asians often appear as early as in the 20 s and 30 s, while age spots in Caucasians tend to become apparent between the ages of 50 and 60 years ⁷⁵⁾.

In the skin, pine bark extract has been found to protect capillary walls ⁷⁶⁾ and to inhibit matrix metalloproteinases ⁷⁷⁾. Direct assessment of the antioxidant effects of pine bark extract by electron spin resonance spectroscopy showed that pine bark extract had significant antioxidant effects on the facial skin of ultraviolet B-irradiated hairless mice in vivo ⁷⁸⁾. Oligometric proanthocyanidins have also been reported to be effective inhibitors of tyrosinase in skin-derived melanocytes and in the hyperpigmented skin of ultraviolet-irradiated mice and guinea pigs ⁷⁹⁾. Oral oligometric proanthocyanidin supplements are expected to have desirable effects on photoaging because they promote tissue elasticity, help heal microinjuries, reduce bruising and swelling by strengthening blood vessels, prevent postinflammatory skin pigmentation, restore dermal collagen, and improve the peripheral circulation ⁸⁰⁾. In fact, oligometric proanthocyanidins from grape seeds have previously been reported to improve melasma to a significant extent ⁸¹⁾.

A white complexion is a highly desirable symbol of beauty among Asian women, who believe that it is powerful enough to hide a number of faults. Pine bark extract did not modify facultative skin color in Furumura et al. ⁸²⁾ trial, suggesting that the skin lightening elicited by pine bark extract is confined to solar lentigines that appear with chronic inflammation, and can persist long after exposure to ultraviolet light. Recent profiling of solar lentigines with cDNA microarrays and immunohistochemical assays revealed a number of upregulated genes for the enzymes that synthesize arachidonic acid, as well as melanogenic and inflammatory genes in those lesions ⁸³⁾.

Modulation of skin pigmentation by oral ingestion of Pycnogenol

There is now also more and more evidence that Pycnogenol may affect pigmentation of human skin. In 2002, Ni et al. ⁸⁴⁾ were first to provide evidence that Pycnogenol intake may reduce hyperpigmentation in women with melasma. In this study, a total of 30 Chinese female patients with melasma orally ingested 75 mg Pycnogenol/day for a total of 1 month. The impact of Pycnogenol intake on preexisting melasma was assessed by means of a clinical score, i.e. the melasma area index, which was based on assessing the diameter of the lesional skin area by means of a ruler. In addition, the pigmentary intensity index was determined by means of a color chart. It was found that after the 30-day treatment period both parameters were significantly reduced. Pycnogenol was well tolerated in all patients, and standard blood and urine parameters did not change. The authors concluded that Pycnogenol is therapeutically effective and safe in patients with melasma, and they attributed the observed beneficial effects to the well-known antioxidative properties of Pycnogenol ⁸⁵⁾. It has to be noted that the design of this study was open, and efficacy parameters were based on subjective assessments. Nevertheless, this study was first to indicate that Pycnogenol intake might be effective to downregulate skin hyperpigmentation. In line with this assumption are in vitro experiments which showed that treatment of cells from the human melanoma cell line B16 with Pycnogenol reduced tyrosinase activity and melanin synthesis in this tumor cell line ⁸⁶⁾. Even more important are results from a recent human in vivo study which provide molecular evidence that the oral intake of Pycnogenol downregulates the expression of genes in human skin which are critically involved in melanin synthesis. The design and part of the results of this clinical trial have previously been published in this journal ⁸⁷⁾. This study is unique because it is the only one to provide in vivo molecular evidence that Pycnogenol uptake is beneficial for human skin. In this clinical trial, a total of 20 healthy postmenopausal Caucasian women were supplemented with 3 × 25 mg Pycnogenol daily for a total of 12 weeks. It was found that this intervention significantly improved skin elasticity and skin hydration, and that this improvement of skin physiological parameters was associated with a significant upregulation of mRNA steady-state levels for hyaluronic acid synthase-1, an enzyme which is important for hyaluronic acid synthesis in skin, as well as genes involved in collagen de novo synthesis. Further RT-PCR analysis of RNA purified from biopsies obtained in this study additionally revealed a significant effect of intake of Pycnogenol on the transcriptional expression of genes which are critically involved in skin pigmentation ⁸⁸⁾. Accordingly, these yet unpublished data, demonstrate that oral Pycnogenol intake was able to significantly inhibit UV radiation-induced upregulation of microphthalmia-associated transcription factor, tyrosinase-related protein 1 and melanoma antigen recognized by T cells, and mRNA expression of tyrosinase was inhibited by trend. These changes provide a molecular basis to explain the previous notion that Pycnogenol intake benefits patients with melasma. The exact mechanism through which Pycnogenol may inhibit the expression of genes involved in skin hyperpigmentation is currently not known. We previously discussed the possibility that Pycnogenol may at least in part function by antagonizing aryl hydrocarbon receptor activation. In this regard it should be noted that aryl hydrocarbon receptor activation in human as well as murine melanocytes has recently been reported to be critically involved in UV radiation-induced skin pigmentation ⁸⁹⁾. Specifically, aryl hydrocarbon receptor activation was shown to cause upregulation of tyrosinase-related proteins 1 and 2 as well as tyrosinase in primary human melanocytes. In aggregate, these studies indicate that the oral intake of Pycnogenol may be used to reduce skin pigmentation in humans in general and hyperpigmentation caused by melasma in particular. Given the central role of microphthalmia-associated transcription factor in the pathogenesis of skin hyperpigmentation and pigmented skin lesions, this should prompt further controlled clinical trials to assess the effect of oral Pycnogenol intake on pigment spot formation in chronically UV-exposed skin areas.

As discussed above, additional studies being done which take into account very recent evidence that skin damage in general and skin hyperpigmentation/skin aging in particular can also be caused by other environmental factors such as nonionizing radiation in the visible as well as infrared range ⁹⁰⁾ and ambient air pollution including traffic-related particulate matter ⁹¹⁾.

Pycnogenol dosage

The following doses have been studied in scientific research:

Adults

By mouth:

• Allergies: 50 mg of a standardized maritime pine bark extract has been used twice daily starting 5 weeks before allergy season.
• Asthma: 1 mg of a standardized maritime pine bark extract per pound of body weight, up to a maximum of 200 mg/day, has been given in two divided doses for one month. Also, 50 mg of the same extract has been used twice daily for 6 months.
• Athletic performance: 100-200 mg a standardized maritime pine bark extract has been used daily for 1-2 months.
• Circulation problems: 45-360 mg of a standardized maritime pine bark extract has been taken daily in up to three divided doses for 3-12 weeks.
• Improving mental function: 150 mg of a standardized maritime pine bark extract has been used daily for 3 months.
• Diseases of the retina in the eye: 50 mg of a standardized maritime pine bark extract has been used three times daily for 2 months.
• Photoaged skin: 40 to 100 mg/day pine bark extract (Flavangenol®) for 12 up to 24 weeks

Children

By mouth:

• Asthma: 1 mg of a standardized maritime pine bark extract per pound of body weight has been taken in two divided doses for 3 months by children and adolescents aged 6-18 years.

Pycnogenol side effects

Pycnogenol is possibly safe when taken by mouth in doses of 50 mg to 450 mg daily for up to one year, and when applied to the skin as a cream for up to 7 days or as a powder for up to 6 weeks. Pycnogenol may can cause dizziness, stomach problems, headache, mouth sores, and bad breath.

Based on data from 70 human clinical studies on 5723 healthy subjects and patients, the overall frequency of adverse side effects due to Pycnogenol is very low (1.8%) and unrelated to dose or duration of use ⁹²⁾. The majority of adverse effects observed are mild. Gastrointestinal discomfort, the most frequently occurring adverse effect, may be avoided by taking Pycnogenol with or after meals. In children with ADHD, 2 of 41 Pycnogenol-supplemented participants experienced side effects (rise of slowness and moderate gastric discomfort). Pycnogenol did not cause any significant changes in blood pressure or heart rate in four clinical studies (total n = 185). There have been no reports of serious adverse effects since its introduction into the European market around 1970 ⁹³⁾. Safety trials have demonstrated the absence of mutagenic and teratogenic effects, no perinatal toxicity and no negative effects on fertility ⁹⁴⁾. Therefore, the use of Pycnogenol in children is considered to be safe ⁹⁵⁾.

Special precautions and warnings

Pregnancy and breast-feeding: Early research suggests that a standardized extract of maritime pine bark (Pycnogenol, Horphag Research) is possibly safe when used in late pregnancy. However, until more is known, it should be used cautiously or avoided by women who are pregnant.

There is not enough reliable information about the safety of taking maritime pine products if you are breast-feeding. Stay on the safe side and avoid use.

Children: A standardized extract of maritime pine bark (Pycnogenol, Horphag Research) is possibly safe when taken by mouth, short-term.

“Auto-immune diseases” such as multiple sclerosis (MS), lupus (systemic lupus erythematosus, SLE), rheumatoid arthritis (RA), or other conditions: Maritime pine might cause the immune system to become more active, and this could increase the symptoms of auto-immune diseases. If you have one of these conditions, it’s best to avoid using maritime pine..

Bleeding conditions: In theory, high doses of maritime pine might increase the risk of bleeding in people with bleeding conditions.

Diabetes: In theory, high doses of maritime pine might decrease blood sugar too much in people with diabetes.

Hepatitis: In theory, taking maritime pine might worsen liver function in people with hepatitis.

Surgery: Maritime pine might slow blood clotting and reduce blood sugar. There is some concern that it might cause blood sugar to go too low and increase the chance of bleeding during and after surgery. Stop using maritime pine at least 2 weeks before a scheduled surgery.

Interactions with medications

Moderate

Be cautious with this combination.

Medications for diabetes (Antidiabetes drugs)

Maritime pine might decrease blood sugar levels. Diabetes medications are also used to lower blood sugar. Taking maritime pine along with diabetes medications might cause your blood sugar to be too low. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed.

Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), and others. The mechanism of action is unclear.

Medications that decrease the immune system (Immunosuppressants)

Maritime pine seems to increase the immune system. By increasing the immune system, maritime pine might decrease the effectiveness of medications that decrease the immune system.

Some medications that decrease the immune system include azathioprine (Imuran), basiliximab (Simulect), cyclosporine (Neoral, Sandimmune), daclizumab (Zenapax), muromonab-CD3 (OKT3, Orthoclone OKT3), mycophenolate (CellCept), tacrolimus (FK506, Prograf), sirolimus (Rapamune), prednisone (Deltasone, Orasone), corticosteroids (glucocorticoids), and others.

Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)

Maritime pine might slow blood clotting. Taking maritime pine along with medications that also slow clotting might increase the chances of bruising and bleeding.

Some medications that slow blood clotting include aspirin, clopidogrel (Plavix), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, ticlopidine (Ticlid), warfarin (Coumadin), and others.

Interactions with herbs and supplements

Herbs and supplements that might lower blood sugar

Maritime pine might lower blood glucose levels. Using it with other herbs or supplements that have the same effect might cause blood sugar levels to drop too low. Some herbs and supplements that can lower blood sugar include alpha-lipoic acid, chromium, devil’s claw, fenugreek, garlic, guar gum, horse chestnut, Panax ginseng, psyllium, Siberian ginseng, and others.

Herbs and supplements that might slow blood clotting

Using maritime pine along with herbs that can slow blood clotting could increase the risk of bleeding in some people. These herbs include angelica, clove, danshen, garlic, ginger, ginkgo, Panax ginseng, and others.

What is phosphatidylserine

Phosphatidylserine (1, 2-diacyl-sn-glycero-3-phospho-L-serine) is the major anionic phospholipid in mammalian cell membranes and phosphatidylserine accounts for 13–15 % of the phospholipids in the human cerebral cortex ¹⁾. The brain is enriched in the two aminophospholipids, phosphatidylethanolamine and phosphatidylserine compared with other tissues. In the brain, and particularly in the retina ²⁾, the acyl chains of phosphatidylserine are highly enriched in docosahexaenoic acid (DHA) ³⁾. In human gray matter, docosahexaenoic acid (DHA) accounts for >36% of the fatty acyl species of phosphatidylserine ⁴⁾. Phosphatidylserine has been shown to play a key role in the functioning of neuron membranes, such as signal transduction, secretory vesicle release and cell-to-cell communication ⁵⁾. With aging, neural membrane fluidity is compromised due to the increased presence of cholesterol, a low incorporation rate and decreased levels of total polyunsaturated fatty acids, blockages to phospholipid pathways, and increases in free radicals, resulting in oxidative stress ⁶⁾. At least 25 clinical trials suggested that consumption of phosphatidylserine supplement may reduce the risk of dementia and cognitive dysfunction in the elderly ⁷⁾, ⁸⁾. The administration of phosphatidylserine extracted from bovine cortex (bovine cortex-phosphatidylserine) has positive effects on brain function. Bovine cortex-phosphatidylserine was shown to improve learning and memory in age-associated memory impaired subjects ⁹⁾, to enhance behavioral and cognitive parameters in geriatric patients ¹⁰⁾, and to improve cognitive performance of Alzheimer’s disease patients ¹¹⁾. However, improvements lasted only a few months and were seen in people with the least severe symptoms. Initially, phosphatidylserine supplements were derived from the brain cells of cows (bovine cortex-phosphatidylserine). The bovine brain cortex phosphatidylserine was found to be enriched with docosahexaenoic acid (DHA) ¹²⁾. But because of concerns about mad cow disease, most manufacturers now produce the supplements from soy lecithin, sunflower lecithin or cabbage derivatives. However, soybean-derived phosphatidylserine does not contain docosahexaenoic acid (DHA), and clinical studies have demonstrated inconclusive efficacy results ¹³⁾. Preliminary studies have shown that plant-based phosphatidylserine supplements may also offer benefits, but more research is needed. However, no modern studies have continued to focus on phosphatidylserine, suggesting its limited effect.

Phosphatidylserine supplement has been approved by the U.S. Food and Drug Administration ¹⁴⁾ to treat memory deficit disorders such as Alzheimer’s disease and other forms of dementia, to support healthy cognitive function during aging, and to remediate cognitive deficits as a result of heavy drinking and cigarette smoking. The mechanism by which phosphatidylserine- omega-3 (DHA) exerts its effects is not fully understood, however phosphatidylserine has been found to regulate key proteins in neuronal membranes, including sodium/calcium ATPase ¹⁵⁾, protein kinase C ¹⁶⁾ and Raf-1 protein kinase ¹⁷⁾. Phosphatidylserine was also found to influence neurotransmitter activity, such as the release of acetylcholine, dopamine and noradrenaline ¹⁸⁾. In addition, phosphatidylserine-omega-3 was found to significantly increase DHA level in brains of middle-aged rats ¹⁹⁾.

Mammalian cell membranes contain >1,000 different phospholipids ²⁰⁾. Phosphatidylcholine is the most abundant phospholipid in mammalian cell membranes, constituting 40–50% of total phospholipids. The second most abundant mammalian membrane phospholipid is phosphatidylethanolamine (PE), which constitutes 20–50% of total phospholipids. In the brain, ∼45% of total phospholipids are phosphatidylethanolamine, whereas in the liver, only ∼20% of total phospholipids are phosphatidylethanolamine. Phosphatidylserine is a quantitatively minor membrane phospholipid that makes up 2–10% of total phospholipids.

In the plasma membrane, phosphatidylserine is localized exclusively in the cytoplasmic leaflet where it forms part of protein docking sites necessary for the activation of several key signaling pathways. These include the Akt, protein kinase C (PKC) and Raf-1 signaling that is known to stimulate neuronal survival, neurite growth and synaptogenesis ²¹⁾. Modulation of the phosphatidylserine level in the plasma membrane of neurons has significant impact on these signaling processes. The mechanism of phosphatidylserine-mediated activation of these neuronal signaling pathways is illustrated in Figure 2.

Figure 1. Phosphatidylserine

Figure 2. Activation of neuronal signaling pathways facilitated by phosphatidylserine

Footnotes: Activation of neuronal signaling pathways facilitated by phosphatidylserine. Activation of Akt, protein kinase C and Raf-1 requires translocation from the cytosol to the cytoplasmic surface of the plasma membrane. Translocation is initiated by specific stimuli, for example, growth factor-dependent PIP₃ generation from PIP₂ by PI3 kinase in the case of Akt. Binding to the membrane occurs in part through an interaction of these proteins with phosphatidylserine present in anionic domains of the lipid bilayer, activating the signaling pathways leading to neuronal differentiation and survival. DHA facilitates this mechanism by increasing phosphatidylserine production in neurons, while ethanol has the opposite effect because it inhibits the DHA-induced increase in PS production.

Abbreviations: PS =phosphatidylserine; R = receptor; DHA = docosahexaenoic acid; PC = phosphatidylcholine; PE = phosphatidylethanolamine

Phosphatidylserine biological function

Phosphatidylserine, a phospholipid with a negatively charged head-group, is an important constituent of eukaryotic cellular membranes. On the plasma membrane, rather than being evenly distributed, phosphatidylserine is found preferentially in the inner leaflet. Disruption of this asymmetry, leading to the appearance of phosphatidylserine on the surface of the cell, is known to play a central role in both apoptosis and blood clotting.

The best-studied roles of phosphatidylserine involve signalling, not within the intracellular environment, but in an extracellular context such as during apoptosis ²³⁾ and during blood clotting. Like most lipids, phosphatidylserine is not evenly distributed throughout all cellular membranes, nor is it always equally distributed between leaflets of a membrane bilayer ²⁴⁾. In healthy cells plasmalemmal phosphatidylserine is exclusively on the inner (cytoplasmic-facing) leaflet due to the action of ATP-dependent aminophospholipid flippases ²⁵⁾. When cells undergo apoptosis (regulated cell death) phosphatidylserine appears on the outside-facing (extracellular) leaflet, signalling phagocytic cells to engulf the dying cell. phosphatidylserine is also exposed exofacially in activated blood platelets, which prompts the binding and activation of a number of clotting factors, including factors V, VIII, X and prothrombin ²⁶⁾.

There is little doubt that, in addition to these extracellular functions, phosphatidylserine plays important roles within the intracellular environment. Indeed, a number of important intracellular proteins require phosphatidylserine for their proper localization and/or activation. Such proteins include the E3 ubiquitin-protein ligase NEDD4, a number of protein kinase C isoforms, several phospholipase C and D isoforms, PTEN ,an important phosphatidylinositol (3,4,5)-trisphosphate phosphatase, dysferlin, a protein important in muscle repair, as well as a number of synaptotagmin isoforms that are important for vesicular trafficking and fusion ²⁷⁾. Additionally, it is known on the whole that phosphatidylserine is important, as mice with a complete loss of ability to synthesize phosphatidylserine are not viable ²⁸⁾, and though yeast are able to survive without phosphatidylserine synthesis, their growth is greatly impaired ²⁹⁾. However, despite the obvious importance of intracellular phosphatidylserine, its distribution, dynamics and function have not been thoroughly investigated.

Cell signaling

Phosphatidylserine(s) are actively held facing the cytosolic (inner) side of the cell membrane by the enzyme flippase. However, when a cell undergoes apoptosis, phosphatidylserine is no longer restricted to the cytosolic side by flippase. Instead scramblase catalyzes the rapid exchange of phosphatidylserine between the two sides. When the phosphatidylserines flip to the extracellular (outer) surface of the cell, they act as a signal for macrophages to engulf the cells ³⁰⁾.

Coagulation

Phosphatidylserine plays a role in blood coagulation (also known as clotting). When circulating platelets encounter the site of an injury, collagen and thrombin -mediated activation causes externalization of phosphatidylserine from the inner membrane layer, where it serves as a pro-coagulant surface ³¹⁾. This surface acts to orient coagulation proteases, specifically tissue factor and factor VII, facilitating further proteolysis, activation of factor X, and ultimately generating thrombin ³²⁾.

In the coagulation disorder Scott syndrome, the mechanism in platelets for transportation of phosphatidylserine from the inner platelet membrane surface to the outer membrane surface is defective ³³⁾. It is characterized as a mild bleeding disorder stemming from the patient’s deficiency in thrombin synthesis ³⁴⁾.

Ethanol-induced effects

Findings in cultured neuronal cells and animal models indicate that ethanol can disrupt the beneficial interaction between DHA and phosphatidylserine. Exposure of Neuro 2A cells to 25 mM ethanol decreased the DHA-mediated accumulation of phosphatidylserine, Akt phosphorylation and cell survival as indicated in Figure 2 above. Administration of ethanol to pregnant rats also decreased the DHA and phosphatidylserine content of the fetal hippocampus and increased the number of apoptotic hippocampal cells ³⁵⁾. Likewise, administration of ethanol to rats during the prenatal and developmental period decreased microsomal phosphatidylserine biosynthetic activity without altering phosphatidylserine synthetase expression, and thus the amount of phosphatidylserine, particularly the 18:0, DHA species in the cerebral cortex ³⁶⁾. The ethanol-mediated decrease in the 18:0, DHA-phosphatidylserine molecular species is also consistent with the finding that incubation of brain microsomes with high concentrations of ethanol increased oleoyl-CoA incorporation into phosphatidylserine and diverted polyunsaturated fatty acids into triglycerides ³⁷⁾. Considering the significant roles played by phosphatidylserine in neuronal survival and function discussed above, a reduction in DHA-stimulated synthesis of phosphatidylserine may be one factor that produces the deleterious effect of ethanol on the central nervous system.

Phosphatidylserine foods

Phosphatidylserine is commonly found in common foods such as meat, fish and legumes,. Currently, dietary intakes of phosphatidylserine, from its natural presence in the diet, is estimated to be in the range of 75 – 184 mg/person/day.

Table 1. Phosphatidylserine content in different foods

Phosphatidylserine synthesis in the brain

In mammalian tissues, phosphatidylserine is synthesized from either phosphatidylcholine or phosphatidylethanolamine exclusively by Ca2+-dependent reactions where the head group of the substrate phospholipids is replaced by serine ³⁹⁾, as illustrated in Figure 3. These base-exchange reactions are catalyzed by phosphatidylserine synthases (PSS) and so far two isoforms, PSS1 and PSS2 encoded by two separate genes, Pss1 and Pss2, respectively, have been identified. PSS1 utilizes phosphatidylcholine as its substrate, and PSS2 utilizes phosphatidylethanolamine. These enzymes are localized in the endoplasmic reticulum, particularly enriched in the mitochondria associated membrane regions of the endoplasmic reticulum ⁴⁰⁾.

Together with testis and kidney, brain is one of the tissues that have high capacity to synthesize phosphatidylserine ⁴¹⁾. Also, the expression of phosphatidylserine synthases (PSS) in the brain is among the highest. The serine base exchange enzymatic activities of rat cerebellar homogenates, cerebral cortical homogenates and cerebral cortical membranes were shown to be recovered in the insoluble floating fraction of TritonX-100 extracts, suggesting the localized presence of phosphatidylserine synthases in membrane lipid rafts ⁴²⁾. Although intriguing, the possible contribution of microsomal contamination cannot be excluded. Phosphatidylserine production is increased in cells of neuronal origin by compounds that trigger Ca²⁺ release, a finding consistent with the fact that phosphatidylserine synthesis is a Ca²⁺-dependent process ⁴³⁾.

Figure 3. Phosphatidylserine synthesis and metabolism in the brain

Footnotes: Phosphatidylserine synthesis and metabolism in the brain. Phosphatidylserine is synthesized by replacement of the choline group of phosphatidylcholine by serine in a reaction catalyzed by phosphatidylserine synthase 1, and also by replacement of the ethanolamine group of phosphatidylethanolamine by serine in a reaction catalyzed by phosphatidylserine synthase 2. These synthetic reactions occur in the endoplasmic reticulum. phosphatidylserine is decarboxylated to phosphatidylethanolamine in the mitochondria by phosphatidylserine decarboxylase (PSD). The phosphatidylethanolamine methyltransferase (PEMT) reaction that utilizes S-adenosylmethionine (SAM) to convert phosphatidylethanolamine to phosphatidylcholine is indicated as a dashed arrow because more recent findings have demonstrated that previously reported methylation activity in the brain is quantitatively insignificant ⁴⁴⁾.

Abbreviations: PC = phosphatidylcholine; PE = phosphatidylethanolamine; PS = phosphatidylserine; PSD = phosphatidylserine decarboxylase; PSS = phosphatidylserine synthases

Composition of brain phosphatidylserine

The phosphatidylserine content in human brain is maintained at the 13–14% level throughout the life ⁴⁶⁾. The fatty acid composition of phosphatidylserine, and for comparison that of phosphatidylethanolamine and phosphatidylcholine, contained in the gray and white matter of human brain, is shown in Table 2 ⁴⁷⁾. There are substantial differences in the fatty acid composition in gray and white matter phosphatidylserine. Gray matter phosphatidylserine contains considerably more DHA and less 18:1n-9 than white matter. Appreciable differences also occur in the phosphatidylethanolamine fatty acid composition in gray and white matter, whereas comparatively small differences occur in the phosphatidylcholine composition. Docosahexaenoic acid (DHA) accounts for more than one-third of the total fatty acid and 80% of the polyunsaturated fatty acid in gray matter phosphatidylserine. A substantial amount of DHA is present in gray matter phosphatidylethanolamine, but only a relatively small amount is present in phosphatidylcholine. Gray matter phosphatidylserine and phosphatidylethanolamine contain considerably more 18:0 and much less 16:0 than phosphatidylcholine. Arachidonic acid is present primarily in phosphatidylethanolamine, and there is little arachidonic acid in phosphatidylserine. According to one study ⁴⁸⁾, phosphatidylethanolamine also contains the largest amount of docosapentaenoic acid, an arachidonic acid-derived product. Only trace amounts of linoleic acid (18:2n-6) are present in brain phosphatidylserine, phosphatidylethanolamine and phosphatidylcholine.

Table 2. Fatty acid composition of human brain glycerophosphatides

Interactions between phosphatidylserine and DHA

Brain is enriched with DHA (docosahexaenoic acid), and the phosphatidylserine content in the grey matter of human brain is particularly high as shown in Table 1. Phosphatidylcholine and phosphatidylethanolamine containing DHA are the best substrate for phosphatidylserine biosynthesis ⁵⁰⁾. As a consequence, the phosphatidylserine level is high in the brain where DHA is abundant. In contrast, DHA-depletion from the brain lowers the phosphatidylserine level ⁵¹⁾. For example, dietary depletion of Omega-3 fatty acids can reduce DHA in the brain and increase the Omega-6 counterpart docosapentaenoic acid. Since phospholipids containing docosapentaenoic acid are not as good substrates for phosphatidylserine synthesis as DHA (docosahexaenoic acid)-containing phospholipid species, the brain phosphatidylserine level is reduced ⁵²⁾. It is important to note that modern western diets are excessively abundant in Omega-6 fatty acids compared to Omega-3 fatty acids, and therefore, DHA enrichment in the brain is compromised as indicated by the considerable accumulation of docosapentaenoic acid observed in the postmortem human hippocampus ⁵³⁾. Such a fatty acid profile is comparable to that observed in rodent brains depleted in DHA at least to a moderate extent, and therefore, the phosphatidylserine level is likely not at a maximum in modern human brains although systematic analysis has not yet been performed.

Phospahtidylserine and cognitive function

A decrease of the DHA content in phosphatidylserine has been reported in cognitive impairment. A small reduction in the DHA content of hippocampal phosphatidylserine was observed in 12 month-old senescence-accelerated prone mice that have a shorter life span, learning and memory deficit, and an increase in hippocampal Aβ-peptide content ⁵⁴⁾. The decrease in DHA was associated with a corresponding increase in the AA content of hippocampal phosphatidylserine. Likewise, the DHA content of phosphatidylserine in the superior temporal and mid-frontal cortex was reduced by 12 and 14 %, respectively, in brain tissues obtained from patients with Alzheimer’s disease ⁵⁵⁾. However, there is no information as to how a decrease in the DHA content of phosphatidylserine might contribute to the pathogenesis of cognitive impairment, and a decrease in DHA content is not a uniform finding in animal models of cognitive impairment. For example, substantial fatty acyl compositional changes, including reductions in AA, have been observed in brain phosphatidylserine of aged Wistar rats with cognitive deficits, but there is no difference in the DHA content of the phosphatidylserine ⁵⁶⁾. Therefore, the putative linkage between DHA reductions in phosphatidylserine and cognitive impairment remains open to question.

Effects of dietary phosphatidylserine supplements on cognitive function

Dietary phosphatidylserine supplements are reported to improve cognitive function in experimental animals ⁵⁷⁾, and a similar result has been obtained recently with krill phosphatidylserine which has a high content of omega-3 fatty acid. Aged rats given daily doses of krill phosphatidylserine orally for 7 days showed improvement in the Morris water maze test. There was less loss of choline acetyltransferase and acetylcholine esterase transporter mRNA in the hippocampus. The neuroprotective activity of 20 mg/kg krill phosphatidylserine was equivalent to that of 50 mg/kg soy phosphatidylserine in these aged rats ⁵⁸⁾. Normal young rats given 100 mg/kg krill phosphatidylserine orally for 30 days also showed improvement in the Morris water maze test ⁵⁹⁾.

Likewise, cognitive improvement was reported in humans given oral phosphatidylserine supplements ⁶⁰⁾, and these findings subsequently were confirmed and extended. Human subjects treated for 42 days with 200 mg of soy-based phosphatidylserine showed a more relaxed state before and after mental stress as measured by electro-encephalography ⁶¹⁾, and no adverse effects were evident at this dose given three-times a day for 6 to 12 weeks ⁶²⁾. The ability to recall words increased by 42% in male and female subjects who were older than 60 years and complained of subjective memory loss when they were treated with 300 mg/day of phosphatidylserine containing 37.5 mg of eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) ⁶³⁾. Improved verbal immediate recall was also observed in a double-blind, placebo controlled clinical trial in a large group of elderly subjects with memory complaints when treated with a daily dose of 300 mg phosphatidylserine containing DHA and eicosapentaenoic acid in a 3:1 ratio. A subset with relatively good cognitive performance at baseline showed the greatest improvement ⁶⁴⁾. In a similar double blind study in Japanese subjects between the ages of 50 and 69 years with memory complaints, subjects having low scores at baseline showed greater improvement in delayed verbal recall after treatment for 6 months with soybean phosphatidylserine ⁶⁵⁾.

Several biochemical responses to phosphatidylserine administration that have been reported in experimental animals could be involved in the mechanism of phosphatidylserine-mediated improvement in cognition. Stimulation of dopamine-dependent adenylate cyclase activity was observed in mouse brain following an intravenous infusion of a sonicated preparation of bovine brain phosphatidylserine ⁶⁶⁾. Sonicated suspensions of phosphatidylserine injected intravenously also increased calcium-dependent acetylcholine output from the cerebral cortex in urethane anesthetized rats ⁶⁷⁾. Likewise, intravenous injection of purified bovine brain phosphatidylserine for 8 days attenuated the decrease in acetylcholine release from the parietal cortex in aged rats, possibly by providing more choline for acetylcholine synthesis ⁶⁸⁾. Furthermore, orally administered krill phosphatidylserine in normal young rats for 30 days produced an increase in neurons positive for brain-derived neurotrophic factor and insulin-like growth factor in the hippocampal CA1 region ⁶⁹⁾.

A current hypothesis is that these biochemical responses and the resulting cognitive improvements are due to phosphatidylserine mediated effects on neuronal membrane properties ⁷⁰⁾. However, experimental evidence indicating that orally or intravenously administered phosphatidylserine actually alters neuronal membrane properties is lacking. How the administered phosphatidylserine is transported in the plasma, how much enters the brain, whether it is taken up intact, and whether it is incorporated into neurons or glia are not known. Dietary phospholipids are hydrolyzed during digestion, so orally administered phosphatidylserine most likely is not absorbed intact. Phosphatidylserine preparations are rich in DHA, and DHA supplementation is known to improve hippocampal function ⁷¹⁾. Because the administered phosphatidylserine probably undergoes partial or complete hydrolysis, the beneficial effects of phosphatidylserine on cognition, particularly from krill or bovine sources, possibly are produced by DHA released from the phosphatidylserine rather than the intact phosphatidylserine itself. These issues will have to be investigated in order to obtain some mechanistic insight into how dietary or intravenously administered phosphatidylserine supplements function to produce cognitive improvement.

Phosphatidylserine summary

A body of evidence supports the functional significance of phosphatidylserine in the brain. Underlying mechanisms are still unfolding; however, phosphatidylserine facilitates the activation of signaling proteins and receptors that are critical for neuronal survival, differentiation and synaptic neurotransmission. Despite its constitutive nature, membrane phosphatidylserine is often an indispensable participant in signaling events and/or influences the signaling in a concentration-dependent manner. The phosphatidylserine biosynthesis preferentially utilizes DHA-containing phospholipids as substrates. Although membrane phospholipids are under a tight homeostatic regulation, the phosphatidylserine level can be altered according to the DHA status, specifically in the brain. Therefore, diet- or ethanol-induced alteration of the brain DHA level and membrane phosphatidylserine can influence the signaling platform in the membrane and the transmission of the signaling cues. Detailed molecular mechanisms, particularly membrane phosphatidylserine-protein interactions, warrant further investigation in order to obtain more insight into the functional significance of neuronal phosphatidylserine. Such endeavor is likely to generate new targets for controlling physiologic or pathophysiologic processes affecting brain function.

Phosphatidylserine dosage

A typical recommended dose of phosphatidylserine as a dietary supplement is 100 mg three times a day (300 mg/day). In numerous human clinical studies, the safety of phosphatidylserine has been confirmed at daily doses of up to 300 mg for up to 6 months ⁷²⁾. The safety of phosphatidylserine has been proven in human clinical studies including susceptible groups (elderly and children) and healthy individuals.

Phosphatidylserine side effects

Phosphatidylserine has been marketed as a dietary supplement for the past two decades without any adverse effects (except gastrointestinal side effects such as nausea and indigestion). A variety of animal toxicity studies and in vitro mutagenicity/genotoxicity studies corroborate the human clinical safety data. The animal studies did not show any significant toxicity at doses up to approximately 1,000 mg/kg/day ⁷³⁾.

What is black cohosh

Black cohosh also known as Cimicifuga racemosa Nuttal or Actaea racemosa L (family Ranunculaceae) is a flowering plant, a member of the buttercup family, native to North America. Other, mostly historical, names for this herb include snakeroot, black bugbane, rattleweed, macrotys, and rheumatism weed ¹⁾. Black cohosh is a coarse, perennial, woodland herb with large compound leaves, and a thick, knotted, rhizome system ²⁾. The underground stems and roots/rhizomes of black cohosh have been used traditionally by Native Americans (Penobscot, Winnebago and Dakota) to treat coughs, colds, constipation, fatigue, malaria ³⁾, impaired kidney function ⁴⁾, sore throat, rheumatism, malaise, menstrual irregularities and childbirth and to stimulate lactation and a variety of conditions related to women’s health ⁵⁾. Since 1832 a hydroalcoholic extract was described as treatment for pain and inflammation in endometriosis and dysmenorrhea ⁶⁾; and a fluid extract was listed in the US National Formulary from 1840 until 1946 ⁷⁾; and was a major constituent of the once popular patent medicine “Lydia Pinkham’s Vegetable Compound” used for treatment of “painful complaints and weakness” in females ⁸⁾. Because of the risks associated with hormone replacement therapy, black cohosh preparations have become popular dietary supplements among women seeking natural treatments for menopausal complaints, because of its purported estrogenic activity ⁹⁾. Currently, women use black cohosh as a dietary supplement for menopausal symptoms, including hot flashes (also called hot flushes) and night sweats (together known as vasomotor symptoms), vaginal dryness, heart palpitations, tinnitus, vertigo, sleep disturbances, nervousness, and irritability ¹⁰⁾. Menopause, which typically occurs in women at about 51 years of age, is the cessation of menstruation and the end of a woman’s reproductive period ¹¹⁾. Black cohosh has also been used as a dietary supplement for other conditions, including menstrual cramps and premenstrual syndrome (PMS), and to induce labor ¹²⁾. The part of the black cohosh plant used in herbal preparations is the root or rhizome (underground stem). The underground stems and root of black cohosh are used fresh or dried to make tea, capsules, pills, or liquid extracts.

Black cohosh key facts

• There is currently insufficient evidence to support the use of black cohosh for menopausal symptoms ¹³⁾. Black cohosh has been studied for menopause symptoms in people, but most of the studies were not of the highest quality. Therefore, knowledge of the effects of black cohosh is limited. However, there is adequate justification for conducting further studies in this area. The uncertain quality of identified trials highlights the need for improved reporting of study methods, particularly with regards to allocation concealment and the handling of incomplete outcome data. The effect of black cohosh on other important outcomes, such as health-related quality of life, sexuality, bone health, night sweats and cost-effectiveness also warrants further investigation.
• Studies that tested black cohosh for menopause symptoms have had inconsistent results. The overall evidence is insufficient to support using black cohosh for this purpose.
• There are not enough reliable data to show whether black cohosh is effective for other uses.

The German Commission E (a German’s equivalent of the U.S. Food and Drug Administration [FDA]) has approved black cohosh for the treatment of premenstrual syndrome, dysmenorrhea, and menopausal symptoms ¹⁴⁾. Although there is little data regarding the precise rate of use among breast cancer patients, black cohosh remains one of the most controversial natural therapies used by this patient population because of its purported phytoestrogenic activity as a selective estrogen receptor modulator (SERM)–like agent ¹⁵⁾. In theory, phytoestrogens possess amphoteric effects on the estrogen receptor (ER). Under conditions of estrogen excess, phytoestrogens may act as estrogen antagonists through competitive inhibition of the estrogen receptor, only stimulating it weakly. Under conditions of low estrogen, phytoestrogens may act as weak agonists ¹⁶⁾. In cases where black cohosh contributes to a net estrogenic effect, its use may result in deleterious effects on breast cancer risk or recurrence ¹⁷⁾. This is of particular concern among women undergoing antiestrogen therapy. Given these conflicting data and the potential for harm, there is an urgent need for a synthesis of available evidence pertaining to the use of black cohosh and its impact on breast cancer risk. A systematic review by Walji et al. ¹⁸⁾ suggested that black cohosh has a high safety profile for use by cancer patients, however, this review has not been updated to include evidence since 2007. Another systematic review done in 2013 ¹⁹⁾ suggests current evidence does not support an association between use of black cohosh and increased risk of breast cancer. That review ²⁰⁾ suggests that black cohosh has limited estrogenic activity. Black cohosh does not appear to possess classical estrogenic activity, as measured by breast and uterine tissue proliferation, but may possibly have nonclassical activities as seen by its effects on bone metabolism. The review shows that black cohosh has no consistent pattern of influence on serum hormone levels [estradiol, luteinizing hormone (LH), or follicle-stimulating hormone (FSH)] or the following estrogen responsive tissues: endometrial tissue, breast tissue, or vaginal tissues ²¹⁾. Black cohosh does seem to stimulate bone formation and may inhibit bone breakdown in women with high bone turnover ²²⁾. In terms of breast cancer risk of 4 studies examining the impact on breast cancer risk, 2 studies found no significant association ²³⁾, ²⁴⁾, and 2 reported an inverse relationship such that black cohosh use was associated with significantly reduced risk of primary breast cancer incidence or breast cancer recurrence, including the study of black cohosh combined with tamoxifen ²⁵⁾, ²⁶⁾. With respect to hot flashes, current evidence is conflicting, with 2 placebo-controlled studies showing no significant effects ²⁷⁾, ²⁸⁾, and 1 study comparing black cohosh plus tamoxifen to tamoxifen alone showing benefit ²⁹⁾. A large placebo effect due to expectation bias may be at play, a real possibility especially given the importance of subjective outcomes in these studies; in addition, one study showing benefits between groups was an open study design, which may introduce bias ³⁰⁾. However, equally plausible is that black cohosh does have some utility in patient with hot flashes.

The popularity of the black cohosh has led to extensive phytochemical and biological investigations, including numerous clinical trials, some of which date back to the 1950s. Despite such extensive research, the clinical efficacy of black cohosh products remains controversial ³¹⁾. Early studies suggested that black cohosh extracts were effective in reducing the frequency and intensity of hot flashes among premenopausal and postmenopausal women ³²⁾, while several recent trials including a Phase II double-blind placebo-controlled trial conducted at the NIH Center for Botanical Dietary Supplements Research demonstrated no vasomotor symptoms benefits ³³⁾. Clinical efficacy is not the only controversy surrounding black cohosh. The question of long-term safety of black cohosh came to light after initial reports of liver failure associated with the use of black cohosh had appeared in the literature ³⁴⁾ The concern was serious enough to warrant two workshops organized by the NIH Office of Dietary Supplements to discuss issues related to safety of black cohosh. A recent review sponsored by the US Pharmacopoeia summarized 30 cases of liver damage associated with black cohosh use and recommended that black cohosh products carry a cautionary statement that they may adversely affect the liver ³⁵⁾. In contrast, several recent reviews of randomized controlled clinical trials concluded that there is no evidence of hepatotoxicity ³⁶⁾ and recent in vitro and animal studies seem to support this conclusion ³⁷⁾.

Figure 1. Black cohosh

When it comes to phytochemical investigations, the past several decades of research have focused almost exclusively on two abundant classes of compounds: triterpene glycosides and phenolic acids. Triterpene glycosides represent the major constituents of all hydroalcoholic black cohosh extracts and have been extensively studied from both the phytochemical and biological side. More than 40 triterpenes have been isolated and structurally characterized to date ³⁸⁾. They represent a particular analytical challenge due to their close structural similarities and overall complexity of distinguishing these structures, which include numerous stereocenters. The most abundant triterpenes, particularly actein (1) and 23-epi-26-deoxyactein (2) [see Figure 2 below), are often used as markers for the standardization of black cohosh preparations ³⁹⁾. Extensive reviews on the chemistry, rational naming system, and biological activities of the triterpenes have been published recently ⁴⁰⁾.

The major phenolic constituents of black cohosh are the hydroxycinnamic acids, caffeic acid (3), ferulic acid (4), and isoferulic acid (5), as well as their condensation products with glycoloyl phenylpropanoids, commonly known as cimicifugic acids [e.g., fukinolic acid (6)] see Figure 3. Numerous members of this class have also been isolated and fully characterized, and a rational naming system has been proposed ⁴¹⁾.

Figure 2. Active compounds from black cohosh

Figure 3. Phenolic constituents of black cohosh

Figure 4. Alkaloids from black cohosh

Black cohosh supplements

Preparations of black cohosh are made from its roots and rhizomes (underground stems). They are sold as dietary supplements in such forms as powdered whole herb, liquid extracts, and dried extracts in pill form.

Available preparations vary considerably in their chemical composition, in part because the compounds in black cohosh that may be responsible for any relief of menopausal symptoms are not known. Substances in black cohosh that may account for its activity include triterpene glycosides such as actein, 23-epi-26-deoxyactein, and cimicifugoside; resins, such as cimicifugin; and aromatic acid derivatives such as caffeic, isoferulic, and fukinolic acids ⁴²⁾.

Products containing black cohosh extract are frequently standardized to provide at least 1 mg triterpene glycosides per daily dose ⁴³⁾. Remifemin, a commercial black cohosh product used in several studies included in a 2012 Cochrane review, is an extract currently standardized to be equivalent to 40 mg black cohosh root/rhizome (extracted with isopropyl alcohol) per daily dose of two tablets, but it is not standardized to triterpene glycoside content. The product has been on the market for years and has been reformulated over time ⁴⁴⁾.

What is blue cohosh

Blue cohosh (Caulophyllum thalictroides) is a native plant grown in eastern United States. As a dietary supplement, blue cohosh is used as an antispasmodic, emenagogue (menstrual flow stimulator), parturifacient (labor inducer), and abortifacient ⁴⁵⁾. In 1999, it was estimated that 64% of American midwives used blue cohosh to induce labor ⁴⁶⁾. Neonates born to women that have taken Blue cohosh (Caulophyllum thalictroides) tincture/dietary supplements may suffer perinatal stroke, acute myocardial infarction, congestive heart failure, neonatal shock, and multiple organ injury ⁴⁷⁾. The side effects associated with blue cohosh administration include diarrhea, increases in blood pressure and blood sugar, and stomach cramps ⁴⁸⁾.

While blue cohosh is known to produce a variety of bioactive natural products, toxic alkaloids (e.g., N-methylcytisine) have been considered the most likely cause of intoxication events ⁴⁹⁾. Blue cohosh (Caulophyllum thalictroides) methanol extract exhibited mitochondriotoxic activity.

Black cohosh for hot flashes and menopausal symptoms

Menopause represents the cessation of menstruation and the end of the reproductive period; this typically occurs around 51 years of age ⁵⁰⁾. Perimenopause is the period of transition to menopause, defined by irregular menstruation within the previous 12 months. Postmenopause is defined as the absence of menstruation for more than 12 months ⁵¹⁾. The events leading to menopause are attributed to a reduction in ovarian activity, which may stem from a physiological or iatrogenic (medically induced) cause. Physiological menopause occurs when the ageing ovaries become less responsive to follicle-stimulating hormone (FSH) and luteinising hormone (LH), resulting in fewer ovulations and decreasing amounts of circulating progesterone and oestrogen. Iatrogenic menopause results from medical intervention, such as oophorectomy (removal of the ovaries), chemotherapy and pelvic irradiation ⁵²⁾. While the severity of symptoms of iatrogenic menopause is somewhat greater than physiological menopause, the types of symptoms reported are similar, with the most common manifestations including vasomotor symptoms (i.e. hot flushes and sweating), vulvovaginal atrophic symptoms (i.e. vaginal atrophy, vaginal dryness) and impaired sexual function ⁵³⁾. The average duration of these symptoms is 3.5 years ⁵⁴⁾, although symptom duration can range anywhere from five months to 10 years, with the severity of these manifestations varying from mild to severe. Postmenopausal women are also at increased risk of osteoporosis ⁵⁵⁾, with the risk escalating with increasing age. This perimenopausal period may be also associated with a decline in quality of life ⁵⁶⁾. In fact, perimenopausal women report a significant decline in perceived physical health and a marginally significant decline in psychosomatic domains (i.e. nervous and emotional state, self confidence, work life, ability to make decisions and ability to concentrate) when compared to premenopausal women ⁵⁷⁾.

Studies using various designs since the 1950s have attempted to determine whether black cohosh affects menopausal symptoms ⁵⁸⁾. Complicating efforts to understand the efficacy of black cohosh for treating menopausal symptoms is the wide variation in the chemical compositions of formulations. Black cohosh’s active ingredients and potential mechanism(s) of action are unknown. Studies have found varying results for the plant’s effects on human physiology as to whether, for example, it raises the body’s levels of estrogen, luteinizing hormone (LH), or follicle-stimulating hormone (FSH), which are all present in lower levels in menopausal women than in premenopausal women ⁵⁹⁾. It is not clear whether black cohosh affects the structure and activity of vaginal and uterine tissues ⁶⁰⁾. Some researchers believe that black cohosh might exert its effects through a brain-related action, such as moduation of serotonergic pathways, or through its potential ability to act as an antioxidant, anti-inflammatory, or selective estrogen receptor modulator ⁶¹⁾.

Two high-quality randomized controlled trials investigating black cohosh for menopausal symptoms are described here. One, published in 2006, assigned 351 women aged 45–55 years experiencing daytime hot flashes and night sweats into one of five groups to take one of the following ⁶²⁾:

1. 160 mg/day black cohosh (70% ethanolic extract standardized to contain 2.5% triterpene glycosides)
2. A multibotanical preparation containing 200 mg black cohosh along with Siberian ginseng, dong quai, and other ingredients
3. The same multibotanical preparation plus two daily servings of soy foods providing 12-20 g soy protein
4. Hormone therapy (estrogen with or without progesterone)
5. A placebo

After 3, 6, and 12 months of supplementation or placebo, the number and intensity of hot flashes and night sweats did not differ between the herbal-intervention groups and the placebo group, with one exception. At 12 months, participants consuming the multibotanical preparation plus soy foods had significantly worse symptom intensity than those consuming the placebo.

Another randomized controlled trial published in 2009 assigned 88 perimenopausal and postmenopausal women (mean age 53 years; 55% from underrepresented minority groups) who were experiencing at least 35 hot flashes and night sweats per week into one of four groups to take one of the following ⁶³⁾:

1. 128 mg/day black cohosh (75% ethanolic extract standardized to contain 5.7% triterpene glycosides)
2. 398 mg/day red clover (ethanolic extract of the aerial parts standardized to 120 mg isoflavones)
3. Hormone therapy (estrogen and progesterone)
4. A placebo

After 3, 6, 9, and 12 months of supplementation or placebo, the number of vasomotor symptoms declined significantly in all groups. However, there were no statistically significant differences between the black cohosh and red clover groups compared to placebo, with one exception. The black cohosh group showed worse symptom intensity at 6 and 9 months. This study also investigated secondary endpoints such as somatic symptoms (e.g., insomnia and fatigue), mood changes (e.g., depression and anxiety), and sexual dysfunction (e.g., vaginal dryness). For most of these outcomes, no significant differences were observed between any of the treatment groups at any time.

A 2012 Cochrane review evaluated 16 randomized clinical trials on the effectiveness of black cohosh in reducing menopausal symptoms, including hot flushes, night sweats, vaginal dryness, and combinations of symptoms measured by validated rating scales ⁶⁴⁾. The 16 included trials randomized a total of 2,027 women (mean age 50.5 to 56.4 years), and their samples ranged from 23 to 351 participants. Study durations were 8 to 54 weeks, with a mean duration of 22.8 weeks. Participants received a daily dose of various formulations of 8 to 160 mg/day black cohosh extract, with a median dose of 40 mg/day. In some cases, the authors of the original study reports indicated that the extract they used came from the root/rhizome, they had extracted the product using isopropyl alcohol or ethanol, and/or they had standardized the extract to contain a specific amount of triterpene glycosides. The studies were highly heterogeneous with respect to such factors as design, duration, type and amount of black cohosh used, and main findings. The review’s authors concluded that there was “insufficient evidence” from these trials “to either support or oppose the use of black cohosh for menopausal symptoms” ⁶⁵⁾.

A 2016 systematic review and meta-analysis of randomized clinical trials examined four studies of herbal and plant-based therapies that included black cohosh to treat menopausal symptoms ⁶⁶⁾. The trials randomized a total of 511 women to a daily dose of various formulations of 6.5 to 160 mg/day black cohosh extract or placebo. There were no significant associations between supplementation with black cohosh and reduction in the number of vasomotor symptoms, such as hot flashes. Furthermore, there were no beneficial associations between black cohosh use and relief of menopausal symptoms using self-reported rating scales.

The American College of Obstetricians and Gynecologists, in its 2015 clinical guidelines for managing menopausal symptoms, concluded that “data do not show that” herbal dietary supplements like black cohosh “are efficacious for the treatment of vasomotor symptoms” ⁶⁷⁾. The North American Menopause Society advises clinicians against recommending herbal therapies such as black cohosh because “they are unlikely to be beneficial” (italics in original) in alleviating vasomotor symptoms ⁶⁸⁾.

The 2012 Cochrane review found adequate justification for conducting further studies on black cohosh’s use to treat menopausal symptoms ⁶⁹⁾. Its authors recommended that researchers conduct higher-quality trials with larger samples and provide more details about their experimental protocols. Others have recommended that researchers should completely and comprehensively describe the black cohosh preparation they used so that other researchers could use the same or similar products ⁷⁰⁾. It is also important to independently analyze and verify the product’s composition to ensure its identity and quality ⁷¹⁾.

Black cohosh dosage

The dose of black cohosh has been reported as ranging from 500-1000 mg daily, for treatment of menopause related disorders like anxiety, depression, flashes and myalgia ⁷²⁾. In that clinical study, the researchers regularly exclude from the treatment patients affected by cancer of sexual organs: breast, ovaries, uterus and hypophysis, unless already treated with conventional therapy from more than 7 years and considered recovered ⁷³⁾.

Black cohosh side effects

The safety of long-term use of black cohosh is uncertain. Clinical trials using various black cohosh preparations to treat menopausal symptoms have shown that its use is associated with a low incidence of adverse effects. The most commonly reported side effects are gastrointestinal upset and rashes, both of which are mild and transient ⁷⁴⁾. Other reported adverse effects in clinical trials have included breast pain/enlargement, infection, vaginal bleeding/spotting, and musculoskeletal complaints, although their incidence was similar in women taking black cohosh and those taking placebo ⁷⁵⁾. Most studies have examined black cohosh use for short periods, typically 6 months or less, so no published studies have assessed the long-term safety of black cohosh in humans.

The safety of black cohosh has become controversial recently following several case reports of liver toxicity ⁷⁶⁾. In July 2006 the European Medicines Agency and the Committee on Herbal Medicinal Products released a public statement ⁷⁷⁾ of case reports of hepatotoxicity (liver injuries) in patients using black cohosh rhizome. Following review of all available data, the European Medicines Agency and the Committee on Herbal Medicinal Products considered that there is a potential connection between herbal medicinal products containing black cohosh rhizome and hepatotoxicity on the base of 42 case reports of hepatotoxicity, collected from European National Competent Authorities (34 cases) as well as literature case reports (8 cases) ⁷⁸⁾. Of these, only 16 cases were considered sufficiently documented to allow the Committee to assess if use of black cohosh rhizome could be linked to the liver injuries. As a result of the assessment, five cases were excluded and seven cases were considered unlikely to be related. In the remaining only four cases (two autoimmune hepatitis, one hepatocellular liver injury and one fulminant hepatic failure), there was a temporal association. So there are very few cases well documented and few data available, for a concrete decision about its suspected hepatotoxicity; and in many reports black cohosh extracts were mixed with many other substances so that was impossible to get any reliable reference to the assumption of black cohosh.

Because black cohosh extracts are sold as over-the-counter integrators, Italian sanitary authorities decided a precautionary withdrawal from the national market, that later has been reversed, and stringent label warnings have been introduced for black cohosh extracts in United Kingdom. So actually there are some concerns about black cohosh extracts safety especially in patients suffering of liver disease.

Across the world, reports have described at least 83 cases of liver damage—including hepatitis, liver failure, elevated liver enzymes, and assorted other liver injuries—associated with black cohosh use ⁷⁹⁾. However, there is no evidence of a causal relationship. It is possible that at least some reported cases of hepatotoxicity were due to impurities, adulterants, or incorrect Acteae species in the black cohosh products used. However, no one independently analyzed these products to confirm the existence of these problems ⁸⁰⁾.

In 2007, the Australian Department of Health began requiring that products containing black cohosh carry the following label statement: “Warning: Black cohosh may harm the liver in some individuals. Use under the supervision of a healthcare professional” ⁸¹⁾. In 2008, the U.S. Pharmacopeia (a nonprofit standard-setting organization for foods and drugs) recommended labeling black cohosh products with the following cautionary statement: “Discontinue use and consult a healthcare practitioner if you have a liver disorder or develop symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice” ⁸²⁾. However, the U.S. Food and Drug Administration does not require such a warning on black cohosh product labels.

The American Herbal Products Association recommends that pregnant women not take black cohosh except under the supervision of their healthcare provider because studies have not rigorously evaluated its use during pregnancy ⁸³⁾. The U.S. Pharmacopeia advises that individuals with liver disorders should also avoid black cohosh ⁸⁴⁾. It adds that users who develop symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice, while taking the supplement should discontinue use and contact their doctor.

Safety of black cohosh in humans

In clinical trials only minor adverse side effects have been reported, including nausea, vomiting, head-aches and dizziness: a review of eight clinical trials concluded that extracts of the rhizome of black cohosh might be a safe alternative for women seeking alternative estrogen replacement therapy ⁸⁵⁾.

• In clinical trials, people have taken black cohosh for as long as 12 months with no serious harmful effects. The only reported side effects were minor problems such as upset stomach or rashes.
• Some commercial black cohosh products have been found to contain the wrong herb or to contain mixtures of black cohosh and other herbs that are not listed on the label.
• Cases of liver damage—some of them very serious—have been reported in people taking commercial black cohosh products. These problems are rare, and it is uncertain whether black cohosh was responsible for them. Nevertheless, people with liver disorders should consult a health care provider before taking black cohosh products, and anyone who develops symptoms of liver trouble, such as abdominal pain, dark urine, or jaundice, while taking black cohosh should stop using it and consult a health care provider.
• The risk of interactions between black cohosh and medicines appears to be small.
• It’s not clear if black cohosh is safe for women who have had hormone-sensitive conditions such as breast cancer or for pregnant women or nursing mothers.
• Black cohosh should not be confused with blue cohosh (Caulophyllum thalictroides), which has different effects and may not be safe. Black cohosh has sometimes been used with blue cohosh to stimulate labor, but this use was linked to severe adverse effects in at least one newborn.

Black Cohosh also contains several catechols, such as caffeic acid, piscidic acid and fukiic acid esters that exhibit some antioxidant properties, including fukinolic acid, cimicifugic acid A and cimicifugic acid B ⁸⁶⁾. Such catechols could be of significant concern in toxicology because of the possibility that they could be activated, either metabolically or chemically, to electrophilic quinones. The potential of such quinones to cause toxicity and carcinogenesis is well documented, and can occur via arylation of cellular proteins and DNA or redox cycling leading to the formation of reactive oxygen species such as the hydroxyl radical ⁸⁷⁾. Nevertheless has been shown in six perimenopausal women after administration of a single dose of either 32, 64 or 128 mg of black cohosh that no corresponding mercapturic acids were found in the urine ⁸⁸⁾. In a previous study, potential toxicity was suspected because catechols from Black Cohosh are activated to quinoid metabolites, but catechols are not absorbed across the bowel.

In a recent trial on 351 randomized women, placebo controlled, Black Cohosh both used as single substance and mixed in multi herbs remedies after 12 month of treatment, did not show any effect on lipids, glucose, insulin and fibrinogen ⁸⁹⁾.

Instead an important issue about safety is probably the interaction with synthetic drugs because of the interference with the metabolic pathway of cytochrome P4503A4 ⁹⁰⁾, a potential cause of important adverse reactions, especially in patients assuming multi drug regimen therapies as confirmed by a recent work in which ethanol and isopropanol extract induced inhibition of CYP1A2, 2C9, 2D6, 3A4.

To be added a case of cutaneous pseudolymphoma in a patient assuming a commercial extract of black cohosh has been reported recently ⁹¹⁾; and a case of muscle damage with asthenia, high levels of creatine phosphokinase and lactate dehydrogenase following assumption of a dietary supplement derived from black cohosh has also been reported ⁹²⁾.

Interactions with tamoxifen and aromatase Inhibitors

The potential for interactions with tamoxifen, in particular aromatase inhibitors, must also be considered. Five studies in our review (4 trials and 1 cohort study) included patients who were receiving both tamoxifen and/or raloxifene ⁹³⁾. None of the trials reported the impact of the combined therapy on risk of recurrence; however, the cohort study by Henneicke-von Zepelin et al. ⁹⁴⁾ suggested that taking black cohosh reduced risk of recurrence by 25% in the treatment group, 35.8% of which was taking tamoxifen ⁹⁵⁾. No consistent serious adverse events related to the combination of black cohosh and tamoxifen was reported by any of the trials ⁹⁶⁾.

An animal study comparing the antitumor effects of formestane with or without the addition of 60 mg/kg isopropanolic black cohosh extract found that the addition of black cohosh had no effect on formestane-induced tumor reduction or reduction of serum estrogen levels ⁹⁷⁾. A second study examining black cohosh with tamoxifen in a model of endometrial cancer found similar results; unlike the endometrial estrogen agonist tamoxifen, “black cohosh did not further growth or metastasizing potential of the primary tumor” ⁹⁸⁾. There were no detectable supportive or antagonistic effects between the 2 treatments ⁹⁹⁾.

In humans, one study reported a statistically significant inhibition of CYP 2D6 by black cohosh ¹⁰⁰⁾. This study used a very high dose of black cohosh (>1000 mg), however, and the magnitude of the effect seen (approximately 7%) “did not appear to be clinically relevant” ¹⁰¹⁾, which cast some doubt on its clinical applicability. Other studies failed to confirm this effect ¹⁰²⁾. Nonetheless, this finding is worth noting, given that tamoxifen, a selective estrogen receptor modulator, is primarily metabolized by CYP 2D6 ¹⁰³⁾. Other inhibitors of CYP 2D6, such as selective serotonin reuptake inhibitors have been shown to reduce serum levels of tamoxifen’s active metabolites, notably endoxifen, by up to 50% ¹⁰⁴⁾. Theoretically, black cohosh might have lesser such effects, though this has not been directly studied. Black cohosh does not appear to affect the following enzymes: CYP 1A2, CYP 2E1, CYP 3A4, CYP 3A5, or Pgp ¹⁰⁵⁾. Conversely, the aromatase inhibitor anastrozole, which is primarily used in postmenopausal women ¹⁰⁶⁾, is metabolized primarly by CYP 3A4 and also to some extent by CYP 3A5, CYP 2C8, and UGT1A4 ¹⁰⁷⁾ suggesting that this drug is less likely to be affected by a pharmacokinetic interaction with black cohosh. The other third generation aromatase inhibitors including letrozole and exemestane are also not affected by CYP 2D6 ¹⁰⁸⁾.

What is red yeast rice

Red yeast rice also known as Hongqu, red Koji, red fermented rice, red kojic rice, red koji rice, anka, or ang-kak, is a bright reddish purple fermented rice, which acquires its color from being cultivated with the mold Monascus purpureus (red yeast of Aspergillaceae family). Red yeast rice is a remedy belonging to Traditional Chinese Medicine, largely used nowadays as dietary supplement in Western countries to improve blood circulation by decreasing cholesterol and triglyceride levels ¹⁾. China is the world’s largest producer of red yeast rice. Red yeast rice supplements contain monacolin K (also known as Mevinolin), which is chemically identical to lovastatin, a licensed drug ²⁾. Lovastatin is associated with various adverse effects such as myopathy and abnormal liver function test results, which can lead to serious problems if patients are not monitored and treated ³⁾. Red yeast rice is often used by statin‐intolerant patients, although there are very few studies testing red yeast rice safety profile as compared to statins. Red yeast rice products may not be safe; some may have the same side effects as certain cholesterol-lowering drugs, and some may contain a potentially harmful contaminant. Clinical trials have reported no significant serious adverse events, but minor events include heartburn ⁴⁾, flatulence ⁵⁾, dizziness ⁶⁾, myalgia ⁷⁾ and loose stools ⁸⁾.

Red yeast rice is produced by first soaking in water until the rice grains are fully saturated. The raw soaked rice can then either be directly inoculated or it can be steamed for the purpose of sterilizing and cooking the grains prior to inoculation. Inoculation is done by mixing a food fungus of the Monascus genus, mainly Monascus purpureus spores or powdered red yeast rice together with the rice that is being treated. The mix is then incubated in an environment around room temperature for 3–6 days. During this period of time, the rice should be fully cultured with Monascus purpureus, with each rice grain turning bright red in its core and reddish purple on the outside. During fermentation the naturally produced pigments give the characteristic red color to the rice and monacolins are produced. As part of the Chinese diet, Red yeast rice is used as food additive to increase the color of meat, fish and soybean products; some preparations of red yeast rice are used in food products in Chinese cuisine, including Peking duck. Moreover, it is recognized as a folk medicine for improving food digestion and blood circulation ⁹⁾. The fully cultured rice is then either sold as the dried grain, or cooked and pasteurized to be sold as a wet paste, or dried and pulverized to be sold as a fine powder.

Key facts

• Some red yeast rice products contain substantial amounts of monacolin K, which is chemically identical to the active ingredient in the cholesterol-lowering drug lovastatin. Lovastatin is one of the drugs in the category known as statins. These drugs lower blood cholesterol levels by reducing the production of cholesterol by the liver. These products may lower blood cholesterol levels and can cause the same types of side effects and drug interactions as lovastatin.
• Other red yeast rice products contain little or no monacolin K. It is not known whether these products have any effect on blood cholesterol levels.
• Consumers have no way of knowing how much monacolin K is present in most red yeast rice products. The labels on these products usually state only the amount of red yeast rice that they contain, not the amount of monacolin K.
• The composition of red yeast rice products varies depending on the yeast strains and culture conditions used to manufacture them. The strains and conditions used to produce culinary red yeast rice differ from those used to produce products that are intended to lower cholesterol. Tests performed by the U.S. Food and Drug Administration (FDA) indicate that the red yeast rice sold as a food product contains only traces of monacolin K or none at all.
• The U.S. Food and Drug Administration (FDA) has determined that red yeast rice products that contain more than trace amounts of monacolin K are unapproved new drugs and cannot be sold legally as dietary supplements.
• Some red yeast rice products contain a contaminant called citrinin, which can cause kidney failure.
• Tell all your health care providers about any complementary health approaches you use. Give them a full picture of what you do to manage your health. This will help ensure coordinated and safe care.

In 1998, the FDA determined that a red yeast rice product that contained a substantial amount of monacolin K was an unapproved new drug, not a dietary supplement. On several occasions since then, the FDA has taken action against companies selling red yeast rice products that contain more than trace amounts of monacolin K, warning them that it is against the law to market these products as dietary supplements.

Despite the FDA actions, some red yeast rice products currently on the market in the United States may contain monacolin K. (Some products tested as recently as 2011 have been found to contain it in substantial amounts.) Other products may contain little or none of this component. Consumers have no way of knowing how much monacolin K is present in most red yeast rice products, and therefore have no way of knowing whether a particular product is safe, effective, or legal. The labels on these products usually state only the amount of red yeast rice that they contain, not the amounts of monacolin K or other monacolins.

Several studies have shown the lipid‐lowering effects of red yeast rice in humans, especially in comparison with placebo in patients intolerant to statins ¹⁰⁾, ¹¹⁾, although only a minority of trials compared head‐to‐head red yeast rice with statins or ezetimibe ¹²⁾, ¹³⁾, and some quality issues (e.g., allocation concealment and blinding) have been raised ¹⁴⁾.

If you are considering red yeast rice

• Do not use red yeast rice to replace conventional care or to postpone seeing your health care provider about a health problem.
• Do not use red yeast rice dietary supplements if you are pregnant, trying to become pregnant, or nursing a child. If you are considering giving a child a red yeast rice dietary supplement, it is especially important to consult the child’s health care provider.
• Do not take red yeast rice in addition to prescription statin drugs.
• Many Web sites, including sales sites, have information about red yeast rice. Be cautious when you evaluate information from the Web; not all of it is trustworthy.
• Federal regulations for dietary supplements are very different from—and less strict than—those for drugs.
• Tell all your health care providers about any complementary health approaches you use. Give them a full picture of what you do to manage your health. This will help ensure coordinated and safe care.

Figure 1. Red yeast rice

Red yeast rice benefits

Red yeast rice products that contain substantial amounts of monacolin K can lower blood cholesterol levels. Researchers have not reported results of any studies of red yeast rice products that contain little or no monacolin K, so whether these products have any effect on blood cholesterol is unknown.

Red yeast rice for cholesterol

In clinical trials (studies in people) of red yeast rice products that contained substantial amounts of monacolin K, the products lowered blood levels of total cholesterol and low-density lipoprotein (LDL) cholesterol (the so-called bad cholesterol that is linked to increased heart disease risk). It is important to emphasize that all of these clinical trials used products that contained substantial amounts of monacolin K. A 2011 analysis showed that some of the red yeast rice products on the market contain very little monacolin K. These products may have little or no effect on blood cholesterol levels. Therefore, even though the participants in the clinical trials were able to lower their cholesterol levels by taking red yeast rice, you might not be able to achieve the same results.

In one of the clinical trials, the tested product produced a cholesterol-lowering effect greater than would be expected based on its monacolin K content. Further investigations, supported by the National Center for Complementary and Integrative Health, suggested that other monacolins or other substances present in the product may have contributed to its cholesterol-lowering effect.

This systematic review ¹⁵⁾ assessed the efficacy and safety of red yeast rice versus simvastatin in the management of dyslipidemia. The evidence suggests that red yeast rice and simvastatin have similar effects in reducing total cholesterol, LDL “bad” cholesterol and triglyceride and increasing HDL “bad” cholesterol. The same adverse events reported between the red yeast rice and simvastatin groups were upset stomach ¹⁶⁾, nausea ¹⁷⁾, abdominal distention ¹⁸⁾, aspartate aminotransferase (AST) increased ¹⁹⁾, alanine aminotransferase (ALT) increased ²⁰⁾ and anorexia ²¹⁾. One trial ²²⁾ reported ‘gastrointestinal symptoms’ as an adverse event in both treatment groups with no further description of symptoms. Dry mouth ²³⁾ and creatine kinase increased ²⁴⁾ were reported only in the simvastatin group. However, because the included trials in this review were of low quality, the review authors are unable to conclusively suggest replacing simvastatin with red yeast rice for the management of dyslipidaemia particularly as red yeast rice is not standardized in active drug content ²⁵⁾. Furthermore, all trial subjects were recruited from Chinese populations ²⁶⁾. Hence, the results of this review may not be applicable to other populations. Therefore, the beneficial effects of red yeast rice over simvastatin need to be established using trials with larger sample size, diverse population, improved methodology and longer duration of treatment ²⁷⁾.

These properties of red yeast rice are due to its monacolins content, a family of naturally occurring substances that inhibit 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase, the rate‐limiting step in cholesterol synthesis. Monacolins content in red yeast rice is usually around 0.4% w/w; of this about 90% consists of monacolin K (also known as Mevinolin) which is chemically identical to lovastatin. Other chemical components of red yeast rice are fatty acids and the pigments monascidin A, ankaflavin, monascorubrine and monascorubramine. A further pigment citrinin, a nephrotoxic mycotoxin, can be produced by some strains of Monascus ²⁸⁾. A dose of red yeast rice containing about 5–7 mg of monacolin K is considered as effective in lowering cholesterol as 20–40 mg of pure lovastatin, probably owing to the presence of other active monacolins or to an increased bioavailability of lovastatin when given as red yeast rice ²⁹⁾. Clinical studies suggest that red yeast rice has the potential to reduce serum LDL “bad” cholesterol levels by 10% to 33% ³⁰⁾, ³¹⁾ and total cholesterol, triglyceride and as well as at increasing HDL “good” cholesterol in people with moderate hypercholesterolemia, but those indicators return to the baseline level when the treatment is discontinued ³²⁾. This phenomenon is similar to statins, which could be explained by the main components of red yeast rice (monacolins, which are capable of inhibiting the HMG-CoA reductase enzyme). In addition to lovastatin, most red yeast rice preparations contain other active substances such as Coenzyme Q10 and isoflavones ³³⁾. Moreover, a recent study showed that the oral bioavailability of lovastatin is significantly improved in red yeast rice products as a result of a higher dissolution rate and reduced crystallinity. This indicates that probably the activity of red yeast rice is much higher than predicted based on the very low doses generally given to patients ³⁴⁾. However, whether red yeast rice preparations should be used as drugs or dietary supplements is still inconclusive. In the US, the FDA recognizes these supplements as drugs when they contain a standardized, specific amount of lovastatin ³⁵⁾. Despite the lipid regulating benefits, some other positive effects of red yeast rice have also been found in studies, such as improving endothelial function and insulin resistance in patients with mild or moderate hypercholesterolemia, reducing high-sensitivity C-reactive Protein (hs-CRP) and markers of vascular remodeling in Italian subjects. Moreover, red yeast rice was proved effective, safe and well tolerated in nephrotic dyslipidemia both in adults and children and in familial hypercholesterolemia children ³⁶⁾.

Tolerability of Red Yeast Rice Products

Two studies supported by National Center for Complementary and Integrative Health have indicated that some people who had been unable to tolerate statin drugs because of side effects (muscle pain or weakness) were able to tolerate red yeast rice. It is uncertain whether the smaller amount of monacolin K in the red yeast rice products, as compared with the amounts of active ingredients in the drugs, accounted for the greater tolerability or whether other factors were responsible.

Red yeast rice dosage

Based on Chinese clinical trials, these are the dosage used: in 19 trials prescribed Xuezhikang 600 mg once daily, one trial used Xuezhikang 600 mg three times daily if the serum total cholesterol or triglyceride is still higher after having been prescribed for 6 weeks (600 mg twice daily in previous 6 weeks) ³⁷⁾, one trial ³⁸⁾ prescribed Xuezhikang 300 mg three times daily, and one trial ³⁹⁾ prescribed Xuezhikang 1200 mg at night. The duration of treatment ranged from 4 weeks to 7 years ⁴⁰⁾. According to the systematic review of Xuezhikang authors (Shang Q, Liu Z, Chen K, Xu H, Liu J. A Systematic Review of Xuezhikang, an Extract from Red Yeast Rice, for Coronary Heart Disease Complicated by Dyslipidemia. Evidence-based Complementary and Alternative Medicine : eCAM. 2012;2012:636547. doi:10.1155/2012/636547. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3332166/)), “before recommending Xuezhikang as an alternative to statins in coronary heart disease patients, more rigorous trials with high quality are needed to give high level of evidence, especially for comparing the effectiveness and safety between Xuezhikang and statins”.

Xuezhikang is a partially purified extract of fermented red yeast rice (Monascus purpureus). It is composed of 13 kinds of natural statins, unsaturated fatty acids, ergosterol, amino acids, flavonoids, alkaloid, trace element, and so forth ⁴¹⁾.

In other clinical trials conducted outside of China, their results are listed in Table 1. The red yeast rice dose per day used range from 500 mg to 3600 mg ⁴²⁾. This meta-analysis included 13 random, placebo-controlled trials containing 804 participants. Red yeast rice showed significant lowering effects on total total cholesterol, triglyceride, and LDL “bad” cholesterol, but did not show a significant increasing effect on HDL “good” cholesterol compared with the placebo group which was different from the result of the last meta-analysis where most of the trials used Xuezhikang as intervention ⁴³⁾. That Chinese meta-analysis suggested that the lipid modification effects of red yeast rice preparations appeared to be similar to simvastatin, atorvastatin, pravastatin, lovastatin or fluvastatin ⁴⁴⁾.

Table 1. Basic characteristics of included red yeast rice trials

Abbreviations: RYR = Red yeast rice, I = Intervention group, C = Control group, I1 = high dose group, I2 = low dose group.

Red yeast rice side effects

Statin drugs such as lovastatin are associated with various side effects such as headache, dizziness, rash, upset stomach, and hepatic dysfunction ⁵⁹⁾. The most common adverse effect is muscle weakness, which can be a sign of more serious myopathy or, in rare cases, rhabdomyolysis. Double-blind, controlled clinical trials have demonstrated that red yeast rice is effective and well tolerated in a wide range of patients ⁶⁰⁾; however, case reports have linked it to muscular myopathy and rhabdomyolysis.

Red yeast rice safety

• The same types of side effects that can occur in patients taking lovastatin as a drug can also occur in patients who take red yeast rice products that contain monacolin K. Potential side effects include myopathy (muscle symptoms such as pain and weakness), rhabdomyolysis (a condition in which muscle fibers break down, releasing substances into the bloodstream that can harm the kidneys), and liver toxicity. Each of these three side effects has been reported in people who were taking red yeast rice.
• Red yeast rice supplements should not be used while pregnant or breastfeeding.
• Lovastatin can interact with a variety of drugs to increase the risk of rhabdomyolysis; these drugs include other cholesterol-lowering agents, certain antibiotics, the antidepressant nefazodone, drugs used to treat fungal infections, and drugs used to treat HIV infection. Red yeast rice containing monacolin K could interact with drugs in the same way.
• If the process of culturing red yeast rice is not carefully controlled, a substance called citrinin can form. Citrinin has been shown to cause kidney failure in experimental animals and genetic damage in human cells. In a 2011 analysis of red yeast rice products sold as dietary supplements, 4 of 11 products were found to contain this contaminant.

Red yeast rice caused or exacerbated myopathy marked by elevated serum creatine kinase levels. Rhabdomyolysis, the most severe adverse effect associated with statins, occurred in a renal transplant patient who used red yeast rice while concomitantly taking cyclosporine ⁶¹⁾. Lovastatin as a prescription drug is contraindicated in pregnancy and is a Category X agent. Category X means studies in animals or humans have demonstrated fetal abnormalities and/or there is positive evidence of human fetal risk based on adverse reaction data from investigational or marketing experience, and the risks involved in use of the drug in pregnant women clearly outweigh potential benefits. This labeling is a main reason for the FDA’s rejection of the application submitted by Merck to sell lovastatin over the counter ⁶²⁾. Red yeast rice, when used by pregnant women, places the fetus at unnecessary risk of central nervous system defects during the first trimester. Although red yeast rice contains a lower dose of lovastatin compared with the FDA-approved product, the risk posed may be similar.

Overall, the findings from Adverse Reactions Surveillance System of Natural Health Products raise the hypothesis that the safety profile of red yeast rice is similar to synthetic statins:

• Myopathies (muscle pain, creatine kinase and transaminases elevation) ⁶³⁾,
• Cutaneous reactions, gastrointestinal and liver reactions emerged as a potential safety signals of red yeast rice and have been reported as not uncommon adverse reactions associated with statins ⁶⁴⁾.

These data are also in line with cases collected from WHO‐Vigibase and reports received by the ANSES French Agency, where muscle‐ and liver‐related adverse reactions were largely reported with red yeast rice 30. In 14 cases (27%), the reactions were serious and mostly required hospitalization, especially those related to liver injury. Most of the reactions involved women, probably because they use more dietary supplements than men ⁶⁵⁾. Notably, some patients who showed muscular adverse reactions associated with statin switched to red yeast rice supplements as an alternative and experienced similar adverse effects ⁶⁶⁾. The time to onset of muscle‐ and liver‐related side effects was relatively rapid: one third of cases occurred during the first month of treatment, and two‐thirds within 60 days.

Therefore, you should know that monacolin K contained in red yeast rice is identical to lovastatin, and you should consider early monitoring of your liver function and become aware of signs of muscle injury. Furthermore, consumers should be discouraged from using red yeast rice preparations as self‐medication, particularly if they have experienced previous adverse reactions to statins ⁶⁷⁾. When self‐prescribed, without medical advice and monitoring and possibly for the long term, patients should be aware they are consuming an active substance, with both therapeutic and toxic effects. In fact, even serious adverse reactions, such as hepatitis or rhabdomyolysis, can remain asymptomatic for long periods with the risk of organ failure progression. In contrast, when statins are taken under medical control, blood tests to check creatine kinase and organ function are performed periodically so that statin use can be stopped as soon as abnormal results are shown.

The potential safety signals of myopathies and liver injury raise the hypothesis that the safety profile of red yeast rice is similar to that of statins.

Red yeast rice complications

Musculoskeletal and connective tissue disorders

Muscular pain, with or without indication of creatine phosphokinase (creatine kinase) increase, occurred in 19 patients, one case of rhabdomyolysis was also recorded. Muscle pain affected generally the lower extremities and cramps were sometimes present. The increase in creatine kinase values was mild in some cases (about 200 U/L or less), high in others (from 288 to 732 U/L) and very high (up to ten times the normal concentrations) in two patients; in the rhabdomyolysis case, the creatine kinase level reached 12,245 U/L. The latency of the reaction was variable, ranging between 9 days and more than one year; however, about one third of the reactions occurred within 30 days and 63% within two months ⁶⁸⁾. Several patients were taking medications, most of which are not known to be associated with muscular disorders, with exception of venlafaxine ⁶⁹⁾; this evidence was taken into account in the causality assessment. Noteworthy, some patients were using red yeast rice preparations as an alternative option, being intolerant to statins, while some patients previously experienced myopathy and creatine kinase increase associated with statin use; patient #15, who showed rhabdomyolysis, presented a previous identical reaction after taking statins; in these cases red yeast rice use was considered a positive rechallenge.

The causality assessment, according to the WHO scale, resulted as possible in 8 cases, probable in 11 cases and certain in case #15 ⁷⁰⁾.

Gastrointestinal disorders

Gastrointestinal reactions occurred in 12 patients and consisted mostly in dyspepsia, nausea, vomiting and abdominal pain, sometimes in diarrhea ⁷¹⁾. The reactions occurred within one or two days or after 3–4 weeks of treatment ⁷²⁾. The reactions were in general not serious, and only one case needed hospitalization ⁷³⁾. Dechallenge was always positive ⁷⁴⁾. Nevertheless, in two patients the reaction, even if improved, was persistent. Five patients had a positive rechallenge. Some cases were judged as possible because similar reactions were reported for concomitant drugs; for example, abdominal pain has been reported in more than 1% of hypertensive patients who received moexipril/hydrochlorotiazide. In causality assessment a conservative approach was used, taking in account that gastrointestinal symptoms such as nausea, vomiting and impaired digestion do not represent specific medical disorders and are common side‐effects of drugs, a positive response to withdrawal and a positive rechallenge.

Hepatobiliary disorders

Hepatic reactions occurred in ten patients and consisted in acute hepatitis (six patients), that required hospitalization, or in increase of hepatic enzymes. These six cases fulfilled criteria for drug‐induced liver injury, according to the international Expert Working Group ⁷⁵⁾. In one patient increase in aspartate aminotransferase (AST) occurred together with creatine phosphokinase (creatine kinase) increase. Nine cases were compatible with the definition of drug‐induced liver injury, as recommended by the International Drug Safety Department ⁷⁶⁾.

Time to onset was between two weeks and one year of treatment, 37% of the reactions occurred within one month and 75% within two months ⁷⁷⁾. Transaminases ranged from about twice to 80 times the upper normal level ⁷⁸⁾. In all cases, except for two in which it was not reported, dechallenge was positive. Patients were taking other drugs or dietary supplements, but generally these were not known to be associated with liver injury ⁷⁹⁾. Case 26 regarded a 49‐year‐old woman who had consumed Armolipid plus® for 50 days. She was hospitalized for suspected myocardial infarction (heart attack); the infarction was excluded, while an acute hepatitis was diagnosed with alanine aminotransferase (ALT) and aspartate aminotransferase (AST) values corresponding to 46 and 57 times the upper normal concentrations, respectively. Total bilirubin was normal, viral and autoimmune serology was negative and other drug and non‐drug causes of hepatitis were excluded; rhabdomyolysis was also excluded. The supplement consumption was suspended and the values decreased, returning to normal after 17 days. The causality assessment resulted in a score of 7 (probable).

Case 27 was a 68‐year‐old woman who had a history of hypercholesterolemia, for which she had been taking the supplement Armolipid plus® for 2 years. An increase of liver enzymes (AST = 87; ALT = 168) was discovered during a routine blood test, and an additional laboratory test reported total bilirubin 0.5, gamma-glutamyl transferase (GGT) 53, ALP 109. Creatine kinase was normal, thus suggesting that the increase in transaminases did not have a muscular aetiology. The ultrasound scan did not show clinically important signs of hepato‐biliary damage, except for moderate steatosis and lithiasis (previously documented). Major infective hepatitis was excluded, no recent flu‐like episodes or gastro‐intestinal symptoms were documented, no history of pre‐existing liver or biliary disease, blood transfusion or alcohol abuse was documented. Concomitant drugs included levothyroxine (for 7 years) and chenodeoxycholic acid (for 5 years). The product was suggested by healthcare professionals because of the patient’s complaints about symptomatic myopathy, probably related to the administration of statins. Notably, no elevation of creatine kinase or hepatic transaminases was previously documented when the woman was treated with statins. The supplement was suspended. Laboratory blood test, performed after less than 4 weeks, gave normal values for AST, ALT, gamma-glutamyl transferase (GGT) and ALP. Based on transaminases values, the liver injury was classified as hepatocellular and the application of the CIOMS/RUCAM scale resulted in a score of 5 (possible).

Skin and subcutaneous disorders

Nine cutaneous reactions associated with red yeast rice products were collected. Most of them occurred with a 1–4‐day latency, the others occurred after 10 days, 3 weeks or about 2 months of treatment ⁸⁰⁾. Four cases were serious and required hospitalization ⁸¹⁾. In one case, which involved a 57‐year‐old woman, the reaction consisted in Pemphigus vulgaris, diagnosed by titration of anti‐desmoglein 1 and 3 antibodies and by biopsy. The reaction occurred 2 weeks after discontinuation of the supplement and needed a pharmacological therapy. The patient was not taking other drugs, but as she had experienced a previous episode of Pemphygus eight years before, then the reaction could be considered a relapse and the causality was judged as unlikely. Another patient a 75‐year‐old woman was admitted to hospital with severe urticaria, rash and edema of the lips. The reaction improved after discontinuation of the red yeast rice supplement but recurred after 6 days, without rechallenge. It is to be underlined that this patient, even without predisposing conditions, was taking various medications (cardioaspirin, amiloride plus hydrochlorothiazide, triazolam, metoprolol, lansoprazole, risedronate), but, most importantly, received flu vaccine 5 days before the onset of the reaction, so, also in this case, the causality was judged as unlikely. In other cases, the causality was judged as possible despite a positive outcome and dechallenge, because patients were taking other drugs, some of which (amiloride plus hydrochlorothiazide, lansoprazole) have been reported to induce cutaneous adverse reactions ⁸²⁾. Another patient was hospitalized for DRESS (drug reaction with eosinophilia and systemic symptoms) syndrome, a severe drug‐induced reaction ⁸³⁾. Laboratory tests suggested that the patient had a Herpes simples virus infection, a condition associated with DRESS ⁸⁴⁾. Cases of DRESS are described also for atorvastatine ⁸⁵⁾, a lipid‐lowering drug belonging to the statins class (as monacolin contained in red yeast rice), as well as for omeprazole ⁸⁶⁾, a proton pump inhibitor similar to pantoprazole that the patient was consuming. Based on these considerations, the causality between DRESS and red yeast rice preparation was judged as possible. In the other cutaneous reactions the causality was considered as probable on the basis of the positive dechallenge, outcome and absence of alternative causes.

Others miscellaneous reactions

A case involved a 78‐year‐old woman who was taking warfarin and showed an increase of INR (international normalized ratio) after consumption of the red yeast rice supplement Armolipid plus®. The dose of warfarin was reduced and the INR value returned to normal. In this case a pharmacodynamic interaction between the anticoagulant drug and red yeast rice supplement can be hypothesized, even if the dechallenge was not done ⁸⁷⁾. Furthermore, three patients showed nausea, vertigo and hazy vision, tingling of extremities and tachycardia; the latter required hospitalization ⁸⁸⁾. Dechallenge was always positive and other causes were excluded, so the causality was judged as probable in all of them ⁸⁹⁾. Nevertheless, it has to be pointed out that in one case the supplement consumed (Fisiostatin®) contained, besides red yeast rice, green tea [Camellia sinensis (L.) O. Kuntze], a source of caffeine that could be responsible for the adverse reaction ⁹⁰⁾.

What is inositol

Inositol (1,2,3,4,5,6‐hexahydroxycyclohexane) is a naturally occurring sugar alcohol, an isomer of glucose, found in cell membrane phospholipids, plasma lipoproteins, and as the phosphate form in the cell nucleus with potential chemopreventive properties ¹⁾. Inositol is an essential nutrient required by human cells in culture for growth and survival ²⁾. There are nine stereoisomers of inositol, of which myo‐, D‐chiro‐, scyllo‐, epi‐, muco‐, and neo‐inositol occur naturally, with the predominant form being myo‐inositol ³⁾. It’s been further observed that the human body (namely liver and kidney) could produce up to 4 g/day on inositol ⁴⁾. Inositol can be synthesized from glucose by means of conversion of glucose 6‐phosphate to inositol 1‐phosphate (Figure 2). Adults typically consume approximately 1 g of myo‐inositol per day which is present in a variety of foods including nuts, whole-grain cereals, plants, vegetables, citrus fruits, fruits and meats ⁵⁾. Plants, particularly legumes, oil seeds, and grains, are particularly rich in myo‐inositol hexakisphosphate (IP6; phytic acid); this is mostly hydrolyzed to free inositol before absorption from the gut ⁶⁾. Given that myo-inositol can be obtained through biosynthetic mechanisms as well as from dietary source, one would surmise that inositol deficiency is unlikely to happen. However, owing to its ion‐chelating properties, an excess of phytate from dietary sources could theoretically hinder absorption of cations, such as Ca2+, from the gut ⁷⁾. Myo‐inositol in the nonphosphorylated form, typically available in vitamin supplements, does not have this property. Although less abundant, D‐chiro‐inositol is also obtained from dietary sources, principally in the methylated form 3‐O‐methyl‐D‐chiro‐inositol (pinitol) ⁸⁾.

Inositol is not a prescription medication, but is widely available as a dietary supplement. Within the body, inositol is used for the production of inositol triphosphate (IP3) and diacylglycerol (DAG), important ‘second messengers’ allowing cell surface receptors for neurotransmitters, including serotonin (5 HT), to affect intracellular processes ⁹⁾. As one of a number of intracellular phosphate compounds, inositol is involved in cell signaling and may stimulate tumor cell differentiation. Inositol has traditionally been considered to be a pseudo‐vitamin B (vitamin Bh or B8) although it has an uncertain status as a vitamin and a deficiency syndrome has not been identified in man ¹⁰⁾. Inositol phospholipids are important in signal transduction. Scyllo-inositol (Scyllitol) has been investigated for the treatment of Alzheimer Disease.

Depletion of cellular content of inositol and of its isomers and phosphate derivatives, has been reported in both diabetic and cancerous tissues ¹¹⁾, while deregulation of myo-inositol metabolism has been found in a number of conditions (PCOS, metabolic syndrome), mechanistically and epidemiologically associated with high-glucose diet or altered glucose metabolism. Inositol deficit may first arise from low nutritional intake of phytate-rich foods, the principal alimentary source of myo-inositol ¹²⁾. High glucose content inhibits myo-inositol uptake by cells, the gut, and the kidney. Moreover, through the activation of the polyol pathway, glucose extrudes myo-inositol from cells, thus “buffering” the increased osmolarity due to the augmented sorbitol levels. Biosynthesis of myo-inositol begins with G-6P enzymatic transformation into inositol-1-phosphate. However, high glucose levels indirectly inhibit myo-inositol biosynthesis, probably by increasing intracellular phosphatidic acid and consequently activating inositol hexakisphosphate kinase (IP6K1), the principal negative regulator of myo-inositol de novo synthesis. Ultimately, glucose increases catabolism and urinary loss of inositol through myo-inositol oxygenase (MIOX) activation and overexpression. To sum up: high glucose levels hinder inositol availability by increasing its degradation and by inhibiting both myo-inositol biosynthesis and absorption ¹³⁾. These underappreciated mechanisms may likely account for acquired, metabolic deficiency in inositol bioavailability. How these effects could participate in the pathogenesis of different degenerative diseases still necessitates further studies.

While a few different hypotheses have been proposed to explain the protective role exerted by diets with high-fiber content ¹⁴⁾, some early reports pointed out the presence of inositol(s) as causative protective agents. Such studies demonstrated that only fibers with high phytate content, such as cereals and legumes, show negative correlation with colon cancer, indicating that phytate, and not fiber, suppressed colon carcinogenesis ¹⁵⁾. Moreover, it was showed that phytic acid exerts some effects originally attributed to fibers. Phytate increases the weights of the cecum and cecal digesta and reduces pH of cecal digesta ¹⁶⁾. In addition, phytate improves the composition of cecal organic acids, microflora, and mucins, and decreases the levels of serum proinflammatory cytokines in rats fed a high-fat, mineral-sufficient diet ¹⁷⁾.

Indeed, myo-Inositol and its phosphate derivatives (namely, inositol-hexaphosphate (IP6) also called phytate, or phytic acid) [inositol pentaphosphate (IP5), tetraphosphate (IP4), and triphosphate (IP3) are also called “phytates”] have been demonstrated to exert a plethora of valuable health effects—including anti-diabetic, anti-oxidant, anti-inflammatory, and anticancer effects ¹⁸⁾. Hence, in recent decades many attempts have been conducted to deepen the understanding of inositol involvement in different physiological and pathological conditions, including fertility ¹⁹⁾, regenerative processes ²⁰⁾, oogenesis ²¹⁾ and sperm function ²²⁾, glucose ²³⁾ and fat metabolism ²⁴⁾, morphogenesis ²⁵⁾, neurological disorders ²⁶⁾, and respiratory function in newborn ²⁷⁾. For instance, in a very preliminary study, F344 rats were injected with azoxymethane to induce colon tumors. Colon cancer development was heralded by the appearance of aberrant crypts in colon epithelium. In the absence of surgical excision, these inflammatory-like lesions progressed towards full neoplastic transformation. Adding Inositol-hexaphosphate (IP6) to the drinking water significantly reduced the number and depth of the colonic crypts, as well as the incidence of colon tumors [83% in controls versus 25% in rats treated with inositol-hexaphosphate (phytate) ²⁸⁾. These preliminary results have been further strengthened by additional investigations, which evidenced that both inositol-hexaphosphate (phytate) and inositol play some appreciable anticancer effects in a number of in vitro and in vivo studies ²⁹⁾.

Inositol polyphosphates are important as second messengers in signal transduction, act as anti-oxidants, and mediate calcium regulation in membrane signaling. Nuclear inositol signaling may also play a role in DNA repair and chromatin remodeling ³⁰⁾. Due to these effects, inositol has been tested in a wide range of human clinical trials, including cancer prevention, autism, and psychiatric disorders. Pre-clinical studies show myo-inositol inhibits carcinogenesis by 40% to 50% in both the induction and post-initiation phase ³¹⁾. In a Randomized phase IIb trial ³²⁾ of myo-Inositol in smokers with bronchial dysplasia were randomly assigned to receive oral placebo or myo-inositol, 9 g once/day for two weeks, and then twice/day for 6 months. Seventy four (n=38 myo-inositol and n=36 placebo) participants with a baseline and 6-month bronchoscopy were included in all efficacy analyses. The complete response and the progressive disease rates were 26.3% versus 13.9% and 47.4% versus 33.3%, respectively, in the myo-inositol and placebo arms. Compared with placebo, myo-inositol intervention significantly reduced IL-6 levels in bronchoalveolar lavage fluid over 6 months ³³⁾. Among those with a complete response in the myo-inositol arm, there was a significant decrease in a gene-expression signature reflective of phosphatidylinositol 3-kinase activation within the cytologically-normal bronchial airway epithelium. The heterogeneous response to myo-inositol suggests a targeted therapy approach based on molecular alterations is needed in future clinical trials to determine the efficacy of myo-inositol as a chemopreventive agent ³⁴⁾.

Lower than normal levels of inositol are found in the cerebrospinal fluid of people with depression ³⁵⁾. Post mortem studies have shown that levels of inositol in particular areas of the cerebral cortex of suicide victims, and people with bipolar disorder are also lowered ³⁶⁾. It has also been reported that the anti-manic effect of lithium treatment is associated with a reduction in inositol levels ³⁷⁾. These findings raised the possibility that increasing inositol levels in depression might be therapeutic. Treatment with inositol has been effective in so-called ‘animal models’ of depression ³⁸⁾. Inositol taken orally has been shown to increase inositol levels within the central nervous system in humans ³⁹⁾. However, based on a Cochrane Systematic Review ⁴⁰⁾, the currently available evidence does not indicate a clear benefit from the use of inositol in depression. It is currently unclear whether or not inositol is of benefit in the treatment of depression. Ongoing studies should reduce this uncertainty. People with depression and their clinicians may wish to await further evidence before using inositol in a widespread fashion.

Figure 1. Inositol (myo-inositol)

Figure 2. Inositol synthesis

Figure 3. Myo-inositol synthesis

Footnotes: (A) Pathways related to glucose 6-phosphate metabolism. Enzyme reactions responsible for the conversion of glucose to myo-inositol are indicated with bold arrows. For simplicity, cofactors are not shown for some of the reactions. (B) The three enzyme reactions responsible for the conversion of glucose to myo-inositol. In the MIPS reaction, NAD⁺ is once reduced to NADH in the first half of the MIPS reaction but is regenerated in the second half of the reaction. (C) The designed pathway for the in vitro conversion of starch or amylose to myo-inositol. Abbreviations: GK, ATP- or ADP-dependent glucokinase; MIPS, myo-inositol-3-phosphate synthase; MalP: maltodextrin phosphorylase; PGM, phosphoglucomutase; IMPase, inositol monophosphatase.

Inositol metabolism

Inositol is chiefly catabolized in the kidney, where the enzyme myo-inositol oxygenase specifically metabolizes myo-inositol through the glucuronate-xylulose pathway. Myo-inositol oxygenase is exclusively expressed in the renal cortical tubules and is markedly downregulated in acute kidney injury ⁴³⁾. Myo-inositol oxygenase catalyzes myo-inositol transformation into d-glucuronic acid, which is further metabolized into l-gulonate by aldehyde reductase. The latter is hence converted into xylulose and ribulose, which finally enter into the glycolytic pathway ⁴⁴⁾.

Nephrectomy in animals impairs myo-inositol degradation, while renal failure is associated with significant abnormalities in myo-inositol metabolism and both inositol plasma and urinary levels ⁴⁵⁾.

Furthermore, elevated inositol excretion (including both myo-inositol and d-Chiro-inositol) have been observed in diabetic animal models characterized by hyperglycemia and glycosuria, regardless of circulating insulin and body weight ⁴⁶⁾. Previous studies on animal models of diabetes documented an increased urinary loss involving only one isomer (myo-inositol or d-Chiro-inositol) ⁴⁷⁾, or both ⁴⁸⁾. Similarly, in humans, increased urinary myo-inositol has been consistently demonstrated in both type 2 diabetes ⁴⁹⁾, and type 1 diabetes ⁵⁰⁾. On the contrary, d-chiro-inositol has been alternatively found increased ⁵¹⁾ or reduced ⁵²⁾. It is noticeable that, despite increased expression of the inositol transporter systems (SMT1/2), inositol reabsorption is significantly inhibited at the tubular level ⁵³⁾. Other pathophysiological processes should therefore explain increased urinary loss of inositol isomers in diabetic kidneys ⁵⁴⁾.

Increased urinary excretion significantly contributes to depleting inositol, and may represent an independent relevant cause of inositol deficiency during both renal failure and diabetes. However, renal depletion of myo-inositol persisted despite normalization of sorbitol levels in diabetic rats treated with an aldose reductase inhibitor, strongly suggesting that inositol depletion occurs independently of the polyol pathway ⁵⁵⁾.

Indeed, it has recently been observed that myo-inositol depletion happens even in insulin-resistant or hypertensive animals, without involvement of the inositol biosynthetic capability, while myo-inositol oxygenase activity steadily increases ⁵⁶⁾. Furthermore, myo-inositol oxygenase overexpression has been already observed in other models of animal diabetes. It is argued that, at least in diabetic, hyperglycemic animals, myo-inositol oxygenase overexpression may be fostered by xylose, an intermediate metabolite of the glucuronate-xylulose pathway (through a positive feedback), and further reinforced by xylulose-5-phosphate, which activates carbohydrate-responsive element binding protein ⁵⁷⁾. In turn, it is worth noting that a sustained activation of the glucuronate-xylulose pathway would be a significant source of oxidative stress ⁵⁸⁾, thus contributing to fibrosis and progressive impairment of renal function ⁵⁹⁾. Conversely, inhibition of myo-inositol oxygenase expression reduces renal (tubular) damage, improving renal function in diabetic animals. Myo-inositol oxygenase overexpression is modulated by glucose-induced transcription factors such as NFAT-5, ChREBP, Nrf-2, AP1, and cAMP-response element-binding protein. Post-translational modifications, chiefly controlled by PKA, PDK1 and PKC, activate myo-inositol oxygenase through phosphorylation of serine and threonine residues, mostly clustered in the N-terminal segment of the myo-inositol oxygenase enzyme ⁶⁰⁾. Aldehyde reductase is also strongly transcriptionally upregulated by high glucose ambience and oxidative stress stemming from the advanced glycation products ⁶¹⁾. Thereby, high glucose levels enhance myo-inositol catabolism by overexpressing and post-translationally activating both myo-inositol oxygenase and aldehyde reductase. It is worth noting that the administration of antioxidants can strongly counteracts these effects, and improves the renal function ⁶²⁾.

These studies suggest a pivotal role of myo-inositol oxygenase in diabetes-associated renal damage. Moreover, as myo-inositol oxygenase overexpression is independent from the glucose-sorbitol pathway, that finding explain why by inhibiting aldose reductase (which catalyzes the main enzymatic step of that pathway) renal function could be only minimally improved in diabetic animals ⁶³⁾.

Diabetic nephropathy may directly arise from myo-inositol oxygenase deregulation, as suggested by studies on renal mitochondria from diabetic animals. Indeed, both in vivo and in vitro investigations revealed that myo-inositol oxygenase upregulation in the presence of high glucose levels induces mitochondrial fragmentation and depolarization, while inhibiting autophagic removal of damaged mitochondria through Pink1-dependent Mfn2–Parkin interaction ⁶⁴⁾. The net effect of these events would be disruption in the surveillance of mitochondrial quality control, accumulation of dysfunctional organelles, generation of reactive oxygen species, and increased apoptosis, leading to tubular injury.

These findings suggest that deregulation of glucose metabolism will trigger abnormalities in myo-inositol metabolism and can increase the production of inositol-dependent toxic metabolites, which ultimately will damage renal function and promote inositol urinary loss. Therefore, it is likely that during hyperglycemia, insulin resistance and/or hypertension, changes in kidney metabolism are directly responsible for increased inositol loss, including both myo-inositol and d-Chiro-inositol isomers ⁶⁵⁾.

What is inositol used for

Inositol and PCOS

There have been a few small clinical trials involving myo-inositol and d-chiro-inositol in PCOS (polycystic ovary syndrome) etiology and therapy. In tissue such as the liver both myo-inositol and d-chiro-inositol are involved in the insulin signaling, i.e. myo-inositol promotes glucose uptake and d-chiro-inositol glycogen synthesis. In reproductive tissue such as the ovary, myo-inositol regulates glucose uptake and follicle stimulating hormone (FSH) signaling, whereas d-chiro-inositol is devoted to the insulin-mediated androgen production. Unlike other tissues, ovary is not insulin resistant, indeed because the epimerase enzyme, which converts myo-inositol to d-chiro-inositol, is insulin dependent, the “d-chiro-inositol paradox” hypothesis suggests that in the ovary of PCOS women, an increased epimerase activity leads to a d-chiro-inositol overproduction and myo-inositol depletion ⁶⁶⁾. This imbalance could be the cause of the poor oocyte quality and the impairment in the FSH signaling. Owing to this situation, the focal point is the administration of both myo-inositol and d-chiro-inositol in a proper ratio for treating PCOS. Insulin resistance plays a pivotal role in PCOS. Insulin-sensitizer agents such as metformin and inositols have been shown to improve the endocrine and metabolic aspects of PCOS ⁶⁷⁾. This study compare the effects of metformin and inositols on the clinical and metabolic features of the women with PCOS. Fifty PCOS women with insulin resistance and/or hyperinsulinemia were randomized to treatment with metformin (1500 mg/day) or myo-inositol (4 g/day). Insulin resistance was defined as HOMA-insulin resistance >2.5, while hyperinsulinemia was defined as a value of area under the curve for insulin after a glucose load over the cutoff of our laboratory obtained in normal women. The women have been evaluated for insulin secretion, BMI, menstrual cycle length, acne and hirsutism, at baseline and after 6 months of therapy. The results obtained in both groups were similar ⁶⁸⁾. The insulin sensitivity improved in both treatment groups. The BMI significantly decreased and the menstrual cycle was normalized in about 50% of the women ⁶⁹⁾. No significant changes in acne and hirsutism were observed. The two insulin-sensitizers, metformin and myo-inositol, show to be useful in PCOS women in lowering BMI and ameliorating insulin sensitivity, and improving menstrual cycle without significant differences between the two treatments ⁷⁰⁾.

Inositol in preterm infants at risk for or having respiratory distress syndrome

In human infants with respiratory distress syndrome (RDS), a premature drop in serum inositol levels predicts a more severe course of the syndrome ⁷¹⁾. Inositol supplementation increases the amount of saturated phosphatidylcholine in surfactant in newborns and produces a rise in serum inositol concentration ⁷²⁾. Inositol promotes maturation of the surfactant phospholipids phosphatidylcholine and phosphatidylinositol, and the synthesis of phosphatidylinositol in type II pneumocytes appears to be dependent on extracellular inositol concentrations ⁷³⁾. Compositional changes in fetal rat lung surfactant correlate with changes in plasma inositol levels, and supplementation increases phospholipid levels to normal in the deprived rat pup ⁷⁴⁾. In humans, free inositol levels in sera from preterm neonates are 2 to 20 times higher than are levels in maternal or adult sera (Bromberger 1986; Burton 1974; Lewin 1978). Studies in newborns suggest an endogenous synthesis of inositol during fetal life (Bromberger 1986; Pereira 1990). Human milk has a high concentration of inositol, with preterm milk being the richest source. Infants who are breast fed have higher serum inositol levels compared to those that are not breastfed at one to two weeks of life ⁷⁵⁾. These facts suggest a critical role for inositol in fetal and early neonatal life. Several studies have been published assessing serum inositol levels in the preterm human infant ⁷⁶⁾, ⁷⁷⁾ as well as the effects of inositol supplementation. As additional evidence has become available, another critical overview of the use of inositol supplementation that includes all known trials to date was warranted. Maintaining inositol concentrations similar to those occurring naturally in utero may reduce the rates of retinopathy of prematurity and bronchopulmonary dysplasia in preterm infants.

Inositol is effective in the management of preterm babies who have or are at a risk of infant respiratory distress syndrome ⁷⁸⁾. Inositol is administered intravenously as long as the infant is not on full oral feeds. When the infant progresses to full feeds inositol is given orally or via an oro-gastric tube. Inositol supplementation results in statistically significant and clinically important reductions in important short-term adverse neonatal outcomes. A large size multi-center randomized controlled trial is currently ongoing and the trial will likely confirm or refute the findings from this Cochrane systematic review.

Inositol and depression

Current scientific evidence does not support the use of inositol for the treatment of depression.

The current evidence for efficacy of inositol for depression consists of inadequate, small, randomized controlled trials and a single meta-analysis, as well as inclusion in a few systematic reviews along with other nutrient-based therapies for depressive disorders.

A 2014 meta-analysis ⁷⁹⁾ of seven randomized controlled trials (two bipolar studies, one bipolar and major depressive disorder study, two major depressive disorder studies, and two premenstrual dysphoric disorder studies) involving 242 participants found no significant treatment effect of inositol for depressed patients. However, inositol showed a trend of efficacy of depressive symptoms over placebo in patients with premenstrual dysphoric disorder.

A 2004 Cochrane review ⁸⁰⁾ of four double-blind, randomized controlled trials involving a total of 141 participants found no clear evidence of a therapeutic benefit.

Inositol dosage

For PCOS the myo-inositol dose used in a clinical trial was 4 g/day ⁸¹⁾.

The myo-inositol through the diet has rarely been investigated, and researchers have to rely on indirect estimations, based on the consumption of phytate-rich aliments. Consuming mostly a vegetarian diet will give you mean daily inositol-hexaphosphate (IP6) intake of 1487 ± 791 mg/day) ⁸²⁾. Moreover, available data evidence shows huge differences among different countries, and an even more relevant variability among different studies performed in the same country. At a first glance, the daily myo-inositol intake does not exceed 500–700 mg/day for western countries, while higher consumption data have been recorded in Africa and Asia. Yet, in both cases, a wide variability has been recorded, probably reflecting hidden diversities (of societal, educational, nutritional origins) among the population under observation. For example, in a study conducted in India, huge differences have been tracked depending on the age and gender of subjects ⁸³⁾. Similar results have been reported among Egyptians ⁸⁴⁾ as well as in many other countries. Moreover, in Europe, contrary to what is generally assumed, inositol-hexaphosphate (phytate) intake is usually far below the supposed daily doses. For instance, in Italy, an early report has documented a broad range of 112–1367 mg phytic acid intake per day with an estimated mean value of 219 mg/day ⁸⁵⁾. A further study stated the mean phytic acid intake of the national Italian diet approximates 293 mg, defined as the average of typical diets from the north-west (288 mg), from the northeast (320 mg), and from the south of Italy (265 mg) ⁸⁶⁾.

Inositol side effects

There is a paucity of data on the safety and side effects of inositol. In a study on myo-inositol some paticipants reported syncope, dyspnea, dizziness, pain, arthralgia and gastrointestinal side effects ⁸⁷⁾. A 2014 meta-analysis of inositol for depression and anxiety disorders found that inositol marginally caused gastrointestinal upset compared with placebo. A 2011 European review on the safety of inositol had similar findings in that inositol induced gastrointestinal side effects such as nausea, flatus, and diarrhea.

What is green coffee

Coffee plants consist of several species such as Coffea arabica, Coffea canephora, Coffea liberica, Coffea excelsa, and Coffea stenophylla ¹⁾. Coffea arabica (Arabica coffee) and Coffea canephora (Robusta coffee) are two most commercially important coffee species ²⁾. Green coffee beans are coffee seeds (beans) of Coffea fruits that have not yet been roasted. The roasting process of coffee beans reduces amounts of the chemical chlorogenic acid (a polyphenol). Therefore, green coffee beans have a higher level of chlorogenic acid compared to regular, roasted coffee beans. Chlorogenic acid (a polyphenol) in green coffee is thought to have health benefits. Of a variety of chlorogenic acids, 5-caffeoylquinic acid has been known to protect tissues from oxidative stress, modulate glucose metabolism, and mediate antiobesity effect ³⁾. Based on an animal study involving mice fed high fat diet ⁴⁾, decaffeinated green coffee bean extract has demonstrated a significant weight-lowering effect in high fat diet-fed mice. Among the green coffee bean extract dosages (0.1%, 0.3%, and 0.9%), 0.3% green coffee bean extract (300 mg green coffee bean extract/kg diet) was proved to be the minimum effective dose for preventing body weight gain, fat accumulation, and insulin resistance in mice fed the high fat diet for 11 weeks ⁵⁾. The dose of 0.3% green coffee bean extract (300 mg green coffee bean extract/kg diet) in mice corresponds to approximately 1,460 mg/60 kg body weight in human when calculated on the basis of normalization to body surface area as recommended by Reagan-Shaw et al. ⁶⁾. No further dose-dependent decreases in body weight gain, visceral fat-pad weights, and plasma lipids and glucose profiles were noted at 0.9% green coffee bean extract dosage. In order to obtain 1.460 mg of decaffeinated green coffee bean extract, 9.7 grams of decaffeinated green coffee beans is required as calculated from its extraction yield of 15%. According to Moon, the content of total chlorogenic acids is reduced by approximately 90% in dark roasted beans ⁷⁾. This implies that 10 times more dark roasted beans (97 grams) are required to produce similar weight-reducing effects as the decaffeinated green coffee beans.

Green coffee beans are a rich source of polyphenols, especially chlorogenic acids. Of a variety of chlorogenic acids, 5-caffeoylquinic acid has been known to protect tissues from oxidative stress, modulate glucose metabolism, and mediate antiobesity effect ⁸⁾. In the mice fed high fat diet study ⁹⁾, 5-caffeoylquinic acid was the most abundant and active component contained in green coffee bean extract and exerted a significant weight-lowering effect in high fat diet-fed mice.

Green coffee extract is a powder extract made of unroasted green coffee beans with potential health effects ¹⁰⁾. In general, green coffee extract can be made of any unroasted green coffee beans, but most of green coffee extract products found in the market are acclaimed to be made of Coffea arabica beans (Arabica coffee). Green coffee extract is present in green or raw coffee ¹¹⁾. Green coffee extract is also present in roasted coffee, but much of the green coffee extract is destroyed during the roasting process. Some green coffee extract constituents, such as chlorogenic acid can also be found in a variety of fruits and vegetables ¹²⁾. The daily intake of chlorogenic acid in persons drinking coffee varies from 0.5 to 1 g ¹³⁾. The traditional method of extraction of green coffee extract from green coffee bean, Coffea canephora robusta, involves the use of alcohol as a solvent ¹⁴⁾. Extracted green coffee extract is marketed as a weight loss supplement under a variety of brand names as a weight loss supplement such as “Coffee Slender”, and “Svetol”.

In animals, green coffee extract has been reported to influence postprandrial glucose concentration and blood lipid concentration ¹⁵⁾. This is thought to be via reduction in the absorption of glucose in the intestine; a mechanism achieved by promoting dispersal of the Na+ electrochemical gradient. This dispersal leads to an influx of glucose into the enterocytes ¹⁶⁾. Green coffee extract is also thought to inhibit the enzymatic activity of hepatic glucose-6-phosphatase, which is involved in the homeostasis of glucose [20]. Reports from animal studies have suggested that green coffee extract mediates its antiobesity effect possibly by suppressing the accumulation of hepatic triglycerides ¹⁷⁾. Some authors have also posited that the antiobesity effect of green coffee extract may be mediated via alteration of plasma adipokine level and body fat distribution and downregulating fatty acid and cholesterol biosynthesis, whereas upregulating fatty acid oxidation and peroxisome proliferator-activated receptor alpha (PPARα) expression in the liver ¹⁸⁾.

Caffeic and quinic acid combine to form chlorogenic acid, which is found in many types of fruit and in high concentrations in coffee: a single cup may contain 70–350 mg chlorogenic acid ¹⁹⁾. The types of fruit having the highest content (blueberries, kiwis, plums, cherries, apples) contain 0.5–2 g hydroxycinnamic acids/kg fresh weight (Table 1) ²⁰⁾. Diets rich in polyphenols may help to prevent various kinds of diseases associated with oxidative stress, including coronary heart disease and some forms of cancer ²¹⁾. Green coffee extract has been reported to have antioxidant activity, demonstrated by its ability to scavenge free radicals in vitro, and to increase the antioxidant capacity of plasma in vivo ²²⁾. Green coffee became popular for weight loss after it was mentioned on the Dr. Oz show in 2012. The Dr. Oz show referred to it as “The green coffee bean that burns fat fast” and claims that no exercise or diet is needed. However, the Federal Trade Commission has sued a Florida-based operation that capitalized on the green coffee diet fad by using bogus weight loss claims and fake news websites to market the dietary supplement pure green coffee ²³⁾. “Not only did these defendants trick consumers with their phony weight loss claims, they also compounded the deception by advertising on pretend news sites, making it impossible for people to know whether they were seeing news or an ad,” said Jessica Rich, Director of the Federal Trade Commission’s Bureau of Consumer Protection ²⁴⁾.

The Federal Trade Commission charged the defendants with false and unsupported advertising claims, including ²⁵⁾:

• that consumers using pure green coffee can lose 20 pounds in four weeks; 16 percent of body fat in twelve weeks; and 30 pounds and four-to-six inches of belly fat in three to five months.
• that studies prove pure green coffee use can result in average weight loss of 17 pounds in 12 weeks or 22 weeks, weight loss of 10.5 percent, and body fat loss of 16 percent without diet or exercise.

The Federal Trade Commission also charged the defendants with deceptively failing to disclose that consumers who endorsed the supplement had received it for free and were paid to provide a video testimonial ²⁶⁾.

People take green coffee by mouth for obesity, diabetes, high blood pressure, Alzheimer’s disease, and bacterial infections. For high blood pressure green coffee might affect blood vessels so that blood pressure is reduced. However, the caffeine found in green coffee might increase blood pressure in people with high blood pressure.

Figure 1. Green coffee beans

Table 1. Polyphenols in foods

Coffee composition

The main coffee constituents are carbohydrates (polysaccharides range from 34 to 44% in Arabica and 48–55% in Robusta coffees), followed by lipids, proteins and peptides, and free sugars ²⁸⁾. The lipid content of coffee is significantly different between Arabica and Robusta, with 15–17% and 7–10% coffee oil for the two species, respectively ²⁹⁾. The sucrose content is reported to have a wide range between batches, from 3.8 to 10.7% (dry weight basis) based on the analysis of 14 species and 6 new taxa, depending on the botanical and geographical origins ³⁰⁾. Green Arabica coffee beans have sucrose content ranging from 6.25 to 8.45%, whereas in Robusta it ranges from 0.9% to 4.85%, with Robusta also containing more reducing sugars ³¹⁾. Other studies have reported sucrose content for Robusta coffee of 4.05–7.05% (dry weight basis) ³²⁾. The post-harvest processing of coffee beans can also dramatically affect composition; for example, ranges of 2.60–3.02% and 6.60–7.02% have been reported for sucrose in dry-processed and wet-processed green coffee ³³⁾.

Among the other compounds in coffee, acids and alkaloids both play a critical role in terms of coffee quality, as they influence the flavour of the beverage. Caffeine is a heat stable methylxanthine, with a distinctive bitter taste and a stimulating effect. Caffeine content in Arabica coffee beans is in the range of 0.90–1.3% ³⁴⁾, while it ranges from 1.51 to 3.33% (dry weight basis) for Robusta ³⁵⁾. Trigonelline is an alkaloid whose synthesis is carried out by enzymatic methylation of nicotinic acid. Its importance in coffee is mainly related to its degradation during roasting to give several volatile compounds; mainly pyrroles and pyridines. Its concentration in Robusta varies from 0.75 to 1.24% (dry weight basis) ³⁶⁾, which is considerably higher than Arabica ³⁷⁾.

Coffee composition is known to vary widely depending on the genotype (Arabica, Coffea arabica, or Robusta, Coffea canephora), environmental factors such as the geographical origin, and post-harvest processing ³⁸⁾. Remarkable differences within the same batch might also be observed, similarly to what has been reported for other crops; e.g. hazelnut plants, which showed significant differences in chemical composition even within the same plant ³⁹⁾.

How effective is green coffee?

Coffee is one of the most widely consumable beverages around the globe nowadays ⁴⁰⁾. The most commercialized coffee species universally are Coffea arabica and Coffea canephora commonly known as arabica and robusta varieties ⁴¹⁾. The arabica variety which is higher in cost than robusta variety due to its lower bitterness, better aroma and flavor is more prized by consumers ⁴²⁾. Coffee is the principal source of bioactive compounds that mainly comprises alkaloids classified as methylxanthines (caffeine, theobromine and theophylline) and trigonelline ⁴³⁾ and the structures of these coffee alkaloids are shown in Figure 2. The two types of alkaloids are derived from nucleotides. These are purine alkaloids like caffeine (1,3,7-trimethylxanthine) and theobromine (3,7-dimethylxanthine) as well as pyridine alkaloid, trigonelline (1-methylnicotinic acid) ⁴⁴⁾. Caffeine and theobromine are essentially found in coffee beans, tea leaves, cacao beans, cola nuts and mate leaves ⁴⁵⁾. But caffeine is the predominant alkaloid in coffee. Even though trigonelline which is the second class of alkaloid occurs in coffee, barley, corn, onion, pea, soybean and tomato, it is the second most abundant alkaloid in coffee ⁴⁶⁾.

Trigonelline and sucrose content is dependent on the coffee genotype, with trigonelline content reported to range from 0.39 to 1.77% (dry weight basis) depending on the species ⁴⁷⁾. However, in contrast, some studies have found that sucrose, caffeine and trigonelline concentrations in green coffee seem not to be significantly affected by the country of origin, nor the genetic groups ⁴⁸⁾. Differences in sucrose content are also linked to the degree of ripening, pre and post-harvest processing ⁴⁹⁾, as well as post-harvest processing ⁵⁰⁾.

Figure 2. Coffee alkaloids structures

Methylxanthines (caffeine and theobromine) were reported to inhibit the elevation of body fat percentage in the developmental stage of rats, improve blood microcirculation and cardiovascular activities, use in the treatment of congestive heart failure and anginal syndrome, reduce the risk of coronary heart disease and stroke, decrease type 2 diabetes mellitus incidence and attribute relevant anti-cancer actions and potential ⁵¹⁾. In addition, caffeine is recognized as a stimulant to the central nervous system and is generally related with enhancement of alertness, learning capacity, relaxation, recreation, providing energy, decrease fatigue, performance enhancement, muscle relaxant when reasonably consumed ⁵²⁾. Theobromine also stimulates the central nervous system to a lower degree than caffeine ⁵³⁾, usually used as smooth muscle relaxant and also causes diuresis ⁵⁴⁾. Trigonelline which is pyridine alkaloid derived from the methylation of the nitrogen atom of nicotinic acid does have hypoglycemic, hypolipidemic, sedative, anti-migraine, anti-bacterial, anti-viral, anti-tumor activities and is able to improve memory, hinder platelet aggregation ⁵⁵⁾ and anti-invasive activity against cancer cells ⁵⁶⁾.

The amount of alkaloids (caffeine, theobromine and trigonelline) in green coffee beans is influenced by numerous factors such as coffee variety, genetic properties of the cultivars, environmental factors (soil, altitude, sun exposure), climatic parameters (rainfall, temperature), maturity of the beans at harvest, harvesting method and agricultural practices (shade, pruning, fertilization) ⁵⁷⁾. For instance, the amount of alkaloids found in green arabica coffee beans were reported in the range 0.87–1.38% (w/w), 0.0048–0.0094% (w/w) and 0.98–1.32% (w/w) for caffeine, theobromine and trigonelline, respectively ⁵⁸⁾ and another report revealed, 0.8–1.4% (w/w), 0.6–1.2% (w/w) for caffeine and trigonelline, respectively, while on the other hand, 1.7–4.0% (w/w), 0.3–0.9% (w/w) for the respective alkaloids in green robusta coffee beans ⁵⁹⁾. However, the content of theobromine in coffee is considerably lower than caffeine and is hardly ever investigated ⁶⁰⁾.

Caffeine and caffeinated coffee have been shown to acutely increase blood pressure and thereby to pose a health threat to persons with cardiovascular disease risk. One short-term study found that ground decaffeinated coffee did not increase blood pressure ⁶¹⁾. Decaffeinated coffee, therefore, may be the type of coffee that can safely help persons decrease diabetes risk. However, the ability of decaffeinated coffee to achieve these effects is based on a limited number of studies, and the underlying biological mechanisms have yet to be elucidated ⁶²⁾.

The effectiveness ratings for green coffee are as follows:

Insufficient evidence to rate effectiveness for:

• High blood pressure. Early research suggests that taking green coffee extracts containing 50 mg to 140 mg of chlorogenic acids daily for 4 weeks to 12 weeks can reduce blood pressure in Japanese adults with mild and untreated high blood pressure. Systolic blood pressure (the top number) appears to be reduced by 5 mmHg to 10 mmHg. Diastolic blood pressure (the bottom number) appears to be reduced by 3 mmHg to 7 mmHg.
• Obesity. Early research shows that adults with obesity who take a specific green coffee extract (Svetol, Naturex) five times daily for 8 weeks to 12 weeks, either alone or together with the regular coffee product Coffee Slender (Med-Eq Ltd., Tonsberg, Norway), lose an average of 2.5 to 3.7 kg more weight than people taking a placebo or regular coffee by itself.
• Alzheimer’s disease.
• Type 2 diabetes.
• Other conditions.

More evidence is needed to rate green coffee for these uses.

Green coffee extract for weight loss

Green coffee extract is present in green or raw coffee ⁶³⁾. Green coffee extract is also present in roasted coffee, but much of the green coffee extract is destroyed during the roasting process. Some green coffee extract constituents, such as chlorogenic acid can also be found in a variety of fruits and vegetables ⁶⁴⁾. The types of fruit having the highest content (blueberries, kiwis, plums, cherries, apples) contain 0.5–2 g hydroxycinnamic acids/kg fresh weight (Table 1) ⁶⁵⁾. The daily intake of chlorogenic acid in persons drinking coffee varies from 0.5 to 1 g ⁶⁶⁾. The traditional method of extraction of green coffee extract from green coffee bean, Coffea canephora robusta, involves the use of alcohol as a solvent ⁶⁷⁾. Extracted green coffee extract is marketed as a weight loss supplement under a variety of brand names as a weight loss supplement such as “Coffee Slender”, and “Svetol”.

In human subjects, coffee intake has been reported to be inversely associated with weight gain ⁶⁸⁾. Consumption of coffee has also been shown to produce changes in several glycemic markers in older adults ⁶⁹⁾. Similarly, other research has indicated that the consumption of caffeinated coffee can lead to some reductions in long-term weight gain, an effect which is likely to be due to the known thermogenic effects of caffeine intake as well as effects of green coffee extract and other pharmacologically active substances present in coffee ⁷⁰⁾. Green coffee extract has also been postulated to modify hormone secretion and glucose tolerance in humans ⁷¹⁾. This effect is accomplished by facilitating the absorption of glucose from the distal, rather than the proximal part of the gastrointestinal tract.

There is also evidence that certain dietary phenols, including green coffee extract, may modify intestinal glucose uptake in a number of ways ⁷²⁾. This activity might provide a basis for explaining its effects on body weight. The purported slimming effect of green coffee extract would have a protective effect against diabetes mellitus, via changes in gastrointestinal hormone secretion ⁷³⁾. A few questions, however, arise from the randomized clinical trials which involve the use of green coffee extract as a weight loss aid.

All the randomized clinical trials involving the use of green coffee extract which have been conducted so far have very small sample sizes, with the largest number of participants being 62 in one trial ⁷⁴⁾. These small sample sizes increase the possibility of spurious or false positive results. Two of the randomized clinical trials were unclear about drop-outs of participants from the trial; neither did they report on intention-to-treat analysis ⁷⁵⁾, ⁷⁶⁾. All of the trials so far identified have been of very short duration. This makes it difficult to assess the efficacy and safety of green coffee extract as a weight reduction agent on the medium to long-term. Although none of the randomized clinical trials identified reported any adverse events, this does not indicate that green coffee extract intake is “risk-free”. Two participants in a study report dropped out due to adverse events associated with the intake of green coffee extract ⁷⁷⁾. These included headache and urinary tract infection. Thus, the safety of this weight loss aid is not established.

The effective dosage of green coffee extract for use as a weight loss supplement is also not established. The dosages of green coffee extract reported in most of the human trials identified were estimated, as the green coffee extract was a component of coffee. While 2 of the randomized clinical trials identified enriched their green coffee extract with chlorogenic acid ⁷⁸⁾, the third trial did not report that the green coffee extract used was fortified with chlorogenic acid ⁷⁹⁾. This warrants further investigation.

The randomized clinical trials identified from a systematic review and meta-analysis of randomized clinical trials ⁸⁰⁾ were not also clear on blinding issues. None of the randomized clinical trials reported on how randomization was carried out, and none provided information regarding blinding of outcome assessors. This casts doubt on the internal validity of these trials. Future trials involving the use of green coffee extract as a weight loss supplement should be conducted in line with the CONSORT (Consolidated Standards of Reporting Trials) guidelines (http://www.consort-statement.org/). This will ensure the validity and applicability of study results. Two authors in one study were affiliated to a company which markets Svetol ⁸¹⁾ but did not specify whether or not they had any conflicts of interest.

Green coffee bean extract and type 2 diabetes

Several studies have identified specific noncaffeine compounds that could affect diabetes risk. Johnston et al ⁸²⁾ reported that 5-caffeoxylquinic acid, the major chlorogenic acid in coffee, may help explain coffee’s ability to decrease diabetes risk in human subjects. They found that the ingestion of either caffeinated or decaffeinated coffee containing equal amounts of chlorogenic acid and glucose caused acute changes in gastrointestinal hormone concentrations. They concluded that chlorogenic acid attenuated the rate of glucose uptake in the proximal small intestine and moved it to more distal regions of the small intestine. Their findings suggest that chlorogenic acid or some other noncaffeine coffee constituents antagonizes caffeine’s stimulation of glucose uptake in the small intestine. Using a sugar absorption test of intestinal permeability, Nieuwenhoven et al ⁸³⁾ found that the addition of caffeine to a sports drink expedited glucose uptake in the small bowel in 10 athletes. The implication is that chlorogenic acid slows the absorption of glucose from the gut, whereas caffeine accelerates it. Rodriguez de Sotillo and Hadley ⁸⁴⁾ found that 3 weeks of intravenous infusion of chlorogenic acid significantly lowered the postprandial peak response to a glucose challenge in insulin-resistant Zucker rats. Chlorogenic acid may have other positive effects on glucose metabolism, including enhancing the antioxidant effects of coffee ⁸⁵⁾, decreasing glucose output in the liver ⁸⁶⁾, and helping preserve β-cell function by promoting the synthesis of the homeodomain transcription factor IDX-1, which helps beta cells respond to increases in plasma glucose ⁸⁷⁾.

It is not known whether tolerance develops to the effects of chlorogenic acid, antioxidants, or other coffee compounds that have the ability to enhance insulin sensitivity. It may be that such tolerance does not develop, even though tolerance to caffeine’s ability to depress insulin sensitivity does develop ⁸⁸⁾. If tolerance to the noncaffeine compounds does not develop, that could help explain the apparent contradiction between the long-term epidemiologic finding that coffee enhances glucose tolerance and the short-term finding that coffee impairs glucose tolerance ⁸⁹⁾.

Green coffee side effects

Green coffee is possibly safe when taken by mouth appropriately. Green coffee extracts taken in doses up to 480 mg daily have been used safely for up to 12 weeks. Also, a specific green coffee extract (Svetol, Naturex, South Hackensack, NJ) has been used safely in doses up to 200 mg five times daily for up to 12 weeks.

It is important to understand that green coffee contains caffeine, similar to regular coffee. Therefore, green coffee can cause caffeine-related side effects similar to coffee.

Caffeine can cause insomnia, nervousness and restlessness, stomach upset, nausea and vomiting, increased heart and breathing rate, and other side effects. Consuming large amounts of coffee might also cause headache, anxiety, agitation, ringing in the ears, and irregular heartbeats.

Special precautions and warnings

Pregnancy and breast-feeding: There is not enough reliable information about the safety of taking green coffee if you are pregnant or breast feeding. Stay on the safe side and avoid use..

Abnormally high levels of homocysteine: Consuming a high dose of chlorogenic acid for a short duration has caused increased plasma homocysteine levels, which may be associated with conditions such as heart disease.

Anxiety disorders: The caffeine in green coffee might make anxiety worse.

Bleeding disorders: There is some concern that the caffeine in green coffee might make bleeding disorders worse.

Diabetes: Some research suggests that caffeine contained in green coffee might change the way people with diabetes process sugar. Caffeine has been reported to cause increases as well as decreases in blood sugar. Use caffeine with caution if you have diabetes and monitor your blood sugar carefully.

Diarrhea: Green coffee contains caffeine. The caffeine in coffee, especially when taken in large amounts, can worsen diarrhea.

Glaucoma: Taking caffeine which is contained in green coffee can increases pressure inside the eye. The increase starts within 30 minutes and lasts for at least 90 minutes.

High blood pressure: Taking caffeine found in green coffee might increase blood pressure in people with high blood pressure. However, this effect might be less in people who consume caffeine from coffee or other sources regularly.

High cholesterol: Certain components of unfiltered coffee have been shown to increase cholesterol levels. These components can be found in green coffee as well. However, it is unclear if green coffee can also cause increased cholesterol levels.

Irritable bowel syndrome (IBS): Green coffee contains caffeine. The caffeine in coffee, especially when taken in large amounts, can worsen diarrhea and might worsen symptoms of IBS.

Thinning bones (osteoporosis): Caffeine from green coffee and other sources can increase the amount of calcium that is flushed out in the urine. This might weaken bones. If you have osteoporosis, limit caffeine consumption to less than 300 mg per day (approximately 2-3 cups of regular coffee). Taking calcium supplements may help to make up for calcium that is lost. Postmenopausal women who have an inherited condition that keeps them from processing vitamin D normally, should be especially cautious when using caffeine.

Green coffee interactions with medications

Moderate interactions

Be cautious with this combination:

Adenosine (Adenocard)

The caffeine in green coffee might block the effects of adenosine (Adenocard). Adenosine (Adenocard) is often used by doctors to do a test on the heart. This test is called a cardiac stress test. Stop consuming green coffee or other caffeine-containing products at least 24 hours before a cardiac stress test.

Alcohol

The body breaks down the caffeine in green coffee to get rid of it. Alcohol can decrease how quickly the body breaks down caffeine. Taking green coffee along with alcohol might cause too much caffeine in the bloodstream and caffeine side effects including jitteriness, headache, and fast heartbeat.

Alendronate (Fosamax)

Green coffee might decrease how much alendronate (Fosamax) the body absorbs. Taking coffee and alendronate (Fosamax) at the same time can decrease the effectiveness of alendronate (Fosamax). Don’t take green coffee within two hours of taking alendronate (Fosamax).

Antibiotics (Quinolone antibiotics)

The body breaks down caffeine from green coffee and other sources to get rid of it. Some antibiotics might decrease how quickly the body breaks down caffeine. Taking these antibiotics along with green coffee can increase the risk of side effects including jitteriness, headache, increased heart rate, and other side effects.

Some antibiotics that decrease how quickly the body breaks down caffeine include ciprofloxacin (Cipro), enoxacin (Penetrex), norfloxacin (Chibroxin, Noroxin), sparfloxacin (Zagam), trovafloxacin (Trovan), and grepafloxacin (Raxar).

Clozapine (Clozaril)

The body breaks down clozapine (Clozaril) to get rid of it. The caffeine in green coffee might decrease how fast the body breaks down clozapine (Clozaril). Taking green coffee along with clozapine (Clozaril) can increase the effects and side effects of clozapine (Clozaril).

Dipyridamole (Persantine)

The caffeine in green coffee might block the effects of dipyridamole (Persantine). Dipyridamole (Persantine) is often used by doctors to do a test on the heart. This test is called a cardiac stress test. Stop taking green coffee or other caffeine-containing products at least 24 hours before a cardiac stress test.

Disulfiram (Antabuse)

The body breaks down the caffeine in green coffee to get rid of it. Disulfiram (Antabuse) can decrease how quickly the body gets rid of caffeine. Taking green coffee along with disulfiram (Antabuse) might increase the effects and side effects of coffee including jitteriness, hyperactivity, irritability, and others.

Ephedrine

Stimulant drugs speed up the nervous system. The caffeine in green coffee and ephedrine are both stimulant drugs. Taking green coffee and ephedrine might cause too much stimulation and sometimes serious side effects and heart problems. Do not take caffeine-containing products and ephedrine at the same time.

Estrogens

The body breaks down the caffeine in green coffee to get rid of it. Estrogens can decrease how quickly the body breaks down caffeine. Taking estrogen pills and green coffee might cause jitteriness, headache, fast heartbeat, and other side effects. If you take estrogen pills limit your caffeine intake.

Some estrogen pills include conjugated equine estrogens (Premarin), ethinyl estradiol, estradiol, and others.

Fluvoxamine (Luvox)

The body breaks down the caffeine in green coffee to get rid of it. Fluvoxamine (Luvox) can decrease how quickly the body breaks down caffeine. Taking caffeine along with fluvoxamine (Luvox) might cause too much caffeine in the body, and increase the effects and side effects of caffeine.

Lithium

Your body naturally gets rid of lithium. The caffeine in green coffee can increase how quickly your body gets rid of lithium. If you take products that contain caffeine and you take lithium, stop taking caffeine products slowly. Stopping caffeine too quickly can increase the side effects of lithium.

Medications for asthma (Beta-adrenergic agonists)

Green coffee contains caffeine. Caffeine can stimulate the heart. Some medications for asthma can also stimulate the heart. Taking caffeine with some medications for asthma might cause too much stimulation and cause heart problems.

Some medications for asthma include albuterol (Proventil, Ventolin, Volmax), metaproterenol (Alupent), terbutaline (Bricanyl, Brethine), and isoproterenol (Isuprel).

Medications for depression (MAOIs)

The caffeine in green coffee can stimulate the body. Some medications used for depression can also stimulate the body. Taking green coffee and taking some medications for depression might cause too much stimulation and serious side effects including fast heartbeat, high blood pressure, nervousness, and others.

Some of these medications used for depression include phenelzine (Nardil), tranylcypromine (Parnate), and others.

Medications that slow blood clotting (Anticoagulant / Antiplatelet drugs)

Caffeine in green coffee might slow blood clotting. Taking green coffee along with medications that also slow clotting might increase the chances of bruising and bleeding.

Some medications that slow blood clotting include aspirin, clopidogrel (Plavix), diclofenac (Voltaren, Cataflam, others), ibuprofen (Advil, Motrin, others), naproxen (Anaprox, Naprosyn, others), dalteparin (Fragmin), enoxaparin (Lovenox), heparin, warfarin (Coumadin), and others.

Pentobarbital (Nembutal)

The stimulant effects of the caffeine in green coffee can block the sleep-producing effects of pentobarbital.

Phenylpropanolamine

The caffeine in green coffee can stimulate the body. Phenylpropanolamine can also stimulate the body. Taking caffeine and phenylpropanolamine together might cause too much stimulation and increase heartbeat, blood pressure, and cause nervousness.

Riluzole (Rilutek)

The body breaks down riluzole (Rilutek) to get rid of it. Taking green coffee can decrease how fast the body breaks down riluzole (Rilutek). In theory, combined use might increase the effects and side effects of riluzole.

Stimulant drugs

Stimulant drugs speed up the nervous system. By speeding up the nervous system, stimulant medications can make you feel jittery and speed up your heartbeat. The caffeine in green coffee can also speed up the nervous system. Taking green coffee along with stimulant drugs might cause serious problems including increased heart rate and high blood pressure. Avoid taking stimulant drugs along with green coffee.

Some stimulant drugs include diethylpropion (Tenuate), epinephrine, phentermine (Ionamin), pseudoephedrine (Sudafed), and many others.

Theophylline

The caffeine in green coffee works similarly to theophylline. Caffeine can also decrease how quickly the body gets rid of theophylline. Taking green coffee and taking theophylline might increase the effects and side effects of theophylline.

Verapamil (Calan, Covera, Isoptin, Verelan)

The body breaks down the caffeine in green coffee to get rid of it. Verapamil (Calan, Covera, Isoptin, Verelan) can decrease how quickly the body gets rid of caffeine. Drinking coffee and taking verapamil (Calan, Covera, Isoptin, Verelan) can increase the risk of side effects for green coffee including jitteriness, headache, and an increased heartbeat.

Minor interactions

Be watchful with this combination:

Birth control pills (Contraceptive drugs)

The body breaks down the caffeine in green coffee to get rid of it. Birth control pills can decrease how quickly the body breaks down caffeine. Taking green coffee along with birth control pills can cause jitteriness, headache, fast heartbeat, and other side effects.

Some birth control pills include ethinyl estradiol and levonorgestrel (Triphasil), ethinyl estradiol and norethindrone (Ortho-Novum 1/35, Ortho-Novum 7/7/7), and others.

Cimetidine (Tagamet)

The body breaks down the caffeine in green coffee to get rid of it. Cimetidine (Tagamet) can decrease how quickly your body breaks down caffeine. Taking cimetidine (Tagamet) along with green coffee might increase the chance of caffeine side effects including jitteriness, headache, fast heartbeat, and others.

Fluconazole (Diflucan)

The body breaks down the caffeine in green coffee to get rid of it. Fluconazole (Diflucan) might decrease how quickly the body gets rid of caffeine. Taking fluconazole (Diflucan) and green coffee might increase the effects and side effects of coffee including nervousness, anxiety, and insomnia.

Medications for diabetes (Antidiabetes drugs)

Caffeine in green coffee might increase blood sugar. Diabetes medications are used to lower blood sugar. By increasing blood sugar, green coffee might decrease the effectiveness of diabetes medications. Monitor your blood sugar closely. The dose of your diabetes medication might need to be changed.

Some medications used for diabetes include glimepiride (Amaryl), glyburide (DiaBeta, Glynase PresTab, Micronase), insulin, pioglitazone (Actos), rosiglitazone (Avandia), chlorpropamide (Diabinese), glipizide (Glucotrol), tolbutamide (Orinase), and others.

Medications for high blood pressure (Antihypertensive drugs)

Green coffee might decrease blood pressure. Taking green coffee along with medications for high blood pressure might cause your blood pressure to go too low.

Some medications for high blood pressure include captopril (Capoten), enalapril (Vasotec), losartan (Cozaar), valsartan (Diovan), diltiazem (Cardizem), Amlodipine (Norvasc), hydrochlorothiazide (HydroDIURIL), furosemide (Lasix), and many others.

Mexiletine (Mexitil)

Green coffee contains caffeine. The body breaks down caffeine to get rid of it. Mexiletine (Mexitil) can decrease how quickly the body breaks down caffeine. Taking Mexiletine (Mexitil) along with green coffee might increase the caffeine effects and side effects of coffee.

Terbinafine (Lamisil)

The body breaks down the caffeine in green coffee to get rid of it. Terbinafine (Lamisil) can decrease how fast the body gets rid of caffeine and increase the risk of side effects including jitteriness, headache, increased heartbeat, and other effects.

Are there interactions with herbs and supplements?

Bitter orange

Bitter orange in combination with caffeine or caffeine-containing herbs can increase blood pressure and heart rate in otherwise healthy adults with normal blood pressure. This might increase the risk of developing serious heart problems. Avoid this combination.

Caffeine-containing herbs and supplements

Using green coffee along with other caffeine-containing herbs and supplements increases exposure to caffeine and increases the risk of developing caffeine-related side effects. Other natural medicines that contain caffeine include black tea, cocoa, cola nut, green tea, oolong tea, guarana, and mate.

Calcium

High caffeine intake from foods and beverages including green coffee increases the amount of calcium that is flushed out in the urine.

Cyclodextrin

The dietary fiber cyclodextrin has been shown to complex with certain components of green coffee that are responsible for its blood pressure-lowering effects. Theoretically, consuming cyclodextrin and green coffee may reduce the absorption of this component and reduce its beneficial effects on blood pressure.

Ephedra (Ma huang)

Green coffee contains caffeine, which is a stimulant. Using green coffee with ephedra, which is also a stimulant, might increase the risk of experiencing serious or life-threatening side effects such as high blood pressure, heart attack, stroke, seizures, and death. Avoid taking coffee with ephedra and other stimulants.

Herbs and supplements that might lower blood pressure

Green coffee decreases blood pressure. When used with other herbs and supplements that reduce blood pressure, green coffee may have additive blood pressure-lowering effects. Other natural medicines with blood pressure-lowering effects include alpha-linolenic acid, blond psyllium, calcium, cocoa, cod liver oil, coenzyme Q-10, garlic, olives, potassium, pycnogenol, sweet orange, vitamin C, wheat bran, and others.

Herbs and supplements that might lower blood sugar

Green coffee extract can lower blood glucose levels. Using it with other herbs or supplements that have the same effect might cause blood sugar levels to drop too low. Some herbs and supplements that can lower blood sugar include alpha-lipoic acid, chromium, devil’s claw, fenugreek, garlic, guar gum, horse chestnut, Panax ginseng, psyllium, Siberian ginseng, and others.

Herbs and supplements that slow blood clotting

The caffeine in green coffee might slow blood clotting. Taking green coffee and using herbs that might also slow blood clotting could increase the risk of bleeding in some people. Some of these herbs include angelica, clove, danshen, garlic, ginger, ginkgo, Panax ginseng, and others.

Iron

Certain components of green coffee may prevent iron from being absorbed from food. Theoretically, this may result in levels of iron in the body becoming too low.

Magnesium

Taking large amounts of green coffee can increase the amount of magnesium that is flushed out in the urine.

What is mucuna pruriens

Mucuna pruriens (Fabaceae) is a tropical legume native to Africa and tropical Asia and widely naturalized and cultivated. Mucuna pruriens other common names include velvet bean, Bengal velvet bean, Florida velvet bean, Mauritius velvet bean, Yokohama velvet bean, cowhage, cowitch, lacuna bean, and Lyon bean ¹⁾. Since Mucuna pruriens is a legume, it fixes nitrogen and fertilizes soil. In Indonesia, particularly Java, the Mucuna pruriens beans are eaten and widely known as ‘Benguk’. The beans can also be fermented to form a food similar to tempe and known as Benguk tempe or ‘tempe Benguk’.

Mucuna pruriens is also a widespread fodder plant in the tropics. To that end, the whole Mucuna pruriens plant is fed to animals as silage, dried hay or dried seeds. Mucuna pruriens silage contains 11-23% crude protein, 35-40% crude fiber, and the dried beans 20-35% crude protein. Mucuna pruriens also has use in the countries of Benin and Vietnam as a biological control for problematic Imperata cylindrica grass ²⁾. Mucuna pruriens is said to not be invasive outside its cultivated area ³⁾. However, the plant is invasive within conservation areas of South Florida, where it frequently invades disturbed land and rockland hammock edge habitats. Mucuna pruriens is sometimes used as a coffee substitute. Cooked fresh shoots or beans can also be eaten.

The hairs lining the Mucuna pruriens seed pods contain serotonin and the protein mucunain which cause severe itching when the pods are touched ⁴⁾. The calyx below the flowers is also a source of itchy spicules and the stinging hairs on the outside of the seed pods are used in itching powder ⁵⁾. Scratching the exposed area can spread the itching to other areas touched. Once this happens, the subject tends to scratch vigorously and uncontrollably and for this reason the local populace in northern Mozambique refer to the beans as “mad beans” (feijões malucos).

Figure 1. Mucuna pruriens

Figure 2. Mucuna pruriens seeds

In addition to the low levels of sulfur-containing amino acids in Mucuna pruriens seeds, the presence of anti-physiological and toxic factors may contribute to a decrease in their overall nutritional quality ⁶⁾. These factors include polyphenols, trypsin inhibitors, phytate, cyanogenic glycosides, oligosaccharides, saponins, lectins, and alkaloids ⁷⁾. Polyphenols (or tannins) are able to bind to proteins, thus lowering their digestibility. Phenolic compounds inhibit the activity of digestive as well as hydrolytic enzymes such as amylase, trypsin, chymotrypsin, and lipase. Recently, phenolics have been suggested to exhibit health related functional properties such as anti-carcinogenic, anti-viral, anti-microbial, anti-inflammatory, hypotensive, and anti-oxidant activities.

Trypsin inhibitors belong to the group of proteinase inhibitors that include polypeptides or proteins that inhibit trypsin activity. Tannins exhibit weak interactions with trypsin, and thus also inhibit trypsin activity. Phytic acid [myoinositol-1,2,3,4,5,6-hexa(dihydrogen phosphate)] is a major component of all plant seeds, which can reduce the bioavailability of certain minerals such as zinc, calcium, magnesium, iron, and phosphorus, as well as trace minerals, via the formation of insoluble complexes at intestinal pH. Phytate-protein complexes may also result in the reduced solubility of proteins, which can affect the functional properties of proteins.

Cyanogenic glycosides are plant toxins that upon hydrolysis, liberate hydrogen cyanide. The toxic effects of the free cyanide are well documented and affect a wide spectrum of organisms since their mode of action is inhibition of the cytochromes of the electron transport system ⁸⁾. Hydrogen cyanide is known to cause both acute and chronic toxicity, but the hydrogen cyanide content of Mucuna pruriens seeds is far below the lethal level. Janardhan et al. ⁹⁾ have investigated the concentration of oligosaccharides in Mucuna pruriens seeds, and verbascose is reportedly the principal oligosaccharide therein ¹⁰⁾. Fatty acid profiles reveal that lipids are a good source of the nutritionally essential linoleic and oleic acids. Linoleic acid is evidently the predominant fatty acid, followed by palmitic, oleic, and linolenic acids ¹¹⁾. The nutritional value of linoleic acid is due to its metabolism at tissue levels that produce the hormone-like prostaglandins. The activity of these prostaglandins includes lowering of blood pressure and constriction of smooth muscle. Phytohemagglutinins (lectins) are substances possessing the ability to agglutinate human erythrocytes.

The major phenolic constituent of Mucuna pruriens beans was found to be levodopa (L-DOPA) (5%), along with minor amounts of methylated and non-methylated tetrahydroisoquinolines (0.25%) ¹²⁾. However, in addition to L-dopa, 5-indole compounds, two of which were identified as tryptamine and 5-hydroxytryptamine, were also reported in Mucuna pruriens seed extracts ¹³⁾. Mucunine, mucunadine, prurienine, and prurieninine are four alkaloids that have been isolated from such extracts ¹⁴⁾. The chemical structures of some of these compounds are shown in Figure 3.

Figure 3. Mucuna pruriens bioactive compounds

Pharmacological effects of Mucuna pruriens extracts

All parts of the Mucuna plant possess medicinal properties ¹⁶⁾. In vitro and in vivo studies on Mucuna pruriens extracts have revealed the presence of substances that exhibit a wide variety of pharmacological effects, including anti-diabetic, anti-inflammatory, neuroprotective and anti-oxidant properties, probably due to the presence of L-dopa, a precursor of the neurotransmitter dopamine (Misra and Wagner, 2007). It is known that the main phenolic compound of Mucuna seeds is L-dopa (approximately 5%) (Vadivel and Pugalenthi, 2008). Nowadays, Mucuna is widely studied because L-dopa is a substance used as a first-line treatment for Parkinson’s disease. Some studies indicate that L-dopa derived from Mucuna pruriens has many advantages over synthetic L-dopa when administered to Parkinson’s patients, as synthetic L-dopa can have several side effects when used for many years.

In small amounts (approximately 0.25%) L-dopa corresponds to methylated and non-methylated tetrahydroisoquinoline ¹⁷⁾. These substances are present in the Mucuna roots, stems, leaves, and seeds. Other substances are present in different parts of the plant, among which are N,N-dimethyl tryptamine and some indole compounds ¹⁸⁾. Alcoholic extracts of the seeds were shown to have potential anti-oxidant activity in in vivo models of lipid peroxidation induced by stress ¹⁹⁾. On the other hand, Spencer et al. ²⁰⁾ have reported that the pro-oxidant and anti-oxidant actions of levodopa (L-DOPA) and its metabolites promote oxidative DNA damage and could also be harmful to tissues damaged by neurodegenerative diseases, namely parkinsonism.

The Mucuna pruriens plant contains relatively high (3–7% dry weight) levels of levodopa (L-DOPA). The levodopa (L-DOPA) content of the raw local velvet bean varieties was 3.75, 3.90, and 4.36% for the white, speckled, and black beans, respectively ²¹⁾. Some people who are sensitive to levodopa (L-DOPA) and may experience nausea, vomiting, cramping, arrhythmias, and hypotension. Up to 99% of the levodopa (L-DOPA) can be leached out of Mucuna pruriens by repeated soaking in boiling water and then cold water. Acidic water significantly increases the rate at which levodopa (L-DOPA) is leached out. Pre-boiling also contributes to better decomposition of anti-nutrients found in Mucuna pruriens through cooking ²²⁾. Soaking Mucuna pruriens grits in 1.5 L, boiling in 1.5 L and then soaking in 1.5 L water for 24 h, all in the presence of sodium bicarbonate (0.25%), extracted the most L-Dopa (90%; from 4.02 to 0.39 %) (Table 1) ²³⁾.

There is some limited evidence that Mucuna pruriens may have beneficial effects on some symptoms of Parkinson’s disease such as motor function because Mucuna pruriens seeds contain levodopa (L-DOPA) ²⁴⁾.

Mucuna pruriens and Parkinson disease research

• A 2018 non-inferiority, randomized, crossover, pilot study ²⁵⁾ with 14 Parkinson’s disease patients received Mucuna pruriens powder and levodopa+carbidopa. Daily intake of Mucuna pruriens resulted in 50% of patients discontinuing uses due to either gastrointestinal side-effects (n = 4) or worsening of motor performance (n = 3). During the levodopa+carbidopa phase no one discontinued use. For patients who tolerated Mucuna pruriens, clinical response was similar to levodopa+carbidopa.
• A 2017 randomized controlled trial ²⁶⁾ of 18 patients with advanced Parkinson’s disease found that Mucuna pruriens powder, at both high and low doses, is as effective and safe as levodopa/benserazide. The clinical response to Mucuna pruriens was similar to the effects of a pharmaceutical preparation of levodopa alone at similar doses, with less side effects. Mucuna pruriens could be a sustainable alternative to marketed levodopa for indigent individuals with Parkinson disease in low-income countries, provided that it is tolerated in the long term.
• A 2004 preliminary pilot study ²⁷⁾ of eight participants with Parkinson’s disease with a short duration L-dopa response and disabling peak dose dyskinesias found that the seed powder formulation of Mucuna pruriens contains a considerable quantity of L-dopa and has a rapid onset of action with a slightly longer duration of therapeutic response compared with standard L-dopa. Mucuna pruriens’s long-term efficacy and safety has not yet been established.

Safety

• The long-term safety of Mucuna pruriens has not yet been established.

Table 1. Levodopa (L-Dopa) content of processed Mucuna pruriens beans, whole and grits

Mucuna pruriens benefits

Mucuna pruriens use in traditional medicine

Mucuna pruriens is a popular Indian medicinal plant, which has long been used in traditional Ayurvedic Indian medicine, for diseases including parkinsonism ²⁹⁾ and as a powerful aphrodisiac ³⁰⁾. Mucuna pruriens have been used to treat nervous disorders and arthritis ³¹⁾. The Mucuna pruriens bean, if applied as a paste on scorpion stings, is thought to absorb the poison ³²⁾.

Anti-epileptic and anti-neoplastic activity of methanol extract of Mucuna pruriens has been reported ³³⁾. A methanol extract of Mucuna pruriens seeds has demonstrated significant in vitro anti-oxidant activity, and there are also indications that methanol extracts of Mucuna pruriens may be a potential source of natural anti-oxidants and anti-microbial agents ³⁴⁾.

All parts of Mucuna pruriens possess valuable medicinal properties and it has been investigated in various contexts, including for its anti-diabetic, aphrodisiac, anti-neoplastic, anti-epileptic, and anti-microbial activities ³⁵⁾. Its anti-venom activities have been investigated by Guerranti et al. ³⁶⁾ and its anti-helminthic activity has been demonstrated by Jalalpure ³⁷⁾. Mucuna pruriens has also been shown to be neuroprotective ³⁸⁾, and has demonstrated analgesic and anti-inflammatory activity ³⁹⁾.

Mucuna pruriens seeds against snake venom poisoning

Mucuna pruriens is one of the plants that have been shown to be active against snake venom and, indeed, its seeds are used in traditional medicine to prevent the toxic effects of snake bites, which are mainly triggered by potent toxins such as neurotoxins, cardiotoxins, cytotoxins, phospholipase A2 (PLA2), and proteases ⁴⁰⁾. In Plateau State, Nigeria, the seed is prescribed as a prophylactic oral anti-snakebite remedy by traditional practitioners, and it is claimed that when the seeds are swallowed intact, the individual is protected for one full year against the effects of any snake bite ⁴¹⁾. The mechanisms of the protective effects exerted by Mucuna pruriens seed aqueous extract (MPE), were investigated in detail, in a study involving the effects of Echis carinatus venom (EV) ⁴²⁾. In vivo experiments on mice showed that protection against the poison is evident at 24 hours (short-term), and 1 month (long term) after injection of Mucuna pruriens seed aqueous extract ⁴³⁾. Mucuna pruriens seed aqueous extract protects mice against the toxic effects of Echis carinatus venom via an immune mechanism ⁴⁴⁾. Mucuna pruriens seed aqueous extract contains an immunogenic component, a multiform glycoprotein, which stimulates the production of antibodies that cross-react with (bind to) certain venom proteins ⁴⁵⁾. This glycoprotein, called gpMuc, is composed of seven different isoforms with molecular weights between 20.3 and 28.7 kDa, and pI between 4.8 and 6.5 ⁴⁶⁾.

It is likely that one or more gpMuc isoform is analogous in primary structure to venom PLA2. The presence of at least one shared epitope has been demonstrated with regard to Mucuna pruriens seeds and snake venom. These cross-reactivity data explain the mechanism of the long-term protection conferred by Mucuna pruriens, and confirm that certain plant species contain PLA2-like proteins, which are beneficial for plant growth, and are involved in important processes ⁴⁷⁾. In addition, Mucuna pruriens seeds contain protein and non-protein components that are able to directly inhibit the activity of proteases and PLA2, and are responsible for short-term protection. In fact, Mucuna pruriens seed aqueous extract contains protease inhibitors that are active against snake venom, in particular a gpMuc isoform sequence also found in a “Kunitz type” trypsin inhibitor contained in soy. Two-dimensional gel electrophoresis has been used to separate the seven gpMuc isoforms, in order to perform N-terminal analysis of each individual isoform. On the other hand, the direct inhibitory action of Mucuna pruriens seed aqueous extract is probably caused by L-dopa, the main bioactive component, which acts in synergy with other compounds.

Anti-microbial properties of Mucuna pruriens leaves

Various parts of certain plants are known to contain substances that can be used for therapeutic purposes or as precursors for the production of useful drugs ⁴⁸⁾. Plant-based anti-microbials represent a vast untapped source of medicines and further investigation of plant anti-microbials is needed. Anti-microbials of plant origin have enormous therapeutic potential. Phytochemical compounds are reportedly responsible for the anti-microbial properties of certain plants ⁴⁹⁾. While bioactive compounds are often extracted from whole plants, the concentration of such compounds within the different parts of the plant varies. Parts known to contain the highest concentration of the compounds are preferred for therapeutic purposes. Some of these active components operate individually, others in combination, to inhibit the life processes of microbes, particularly pathogens. Crude methanolic extracts of Mucuna pruriens leaves have been shown to have mild activity against some bacteria in experimental settings, probably due to the presence of phenols and tannins ⁵⁰⁾. Further studies are required in order to isolate the bioactive components responsible for the observed anti-microbial activity.

Neuroprotective effect of Mucuna pruriens seeds

In India, the seeds of Mucuna pruriens have traditionally been used as a nervine tonic, and as an aphrodisiac for male virility. The pods are anthelmintic, and the seeds are anti-inflammatory. Powdered seeds possess anti-parkinsonism properties, possibly due to the presence of L-dopa (a precursor of neurotransmitter dopamine). It is well known that dopamine is a neurotransmitter. The dopamine content in brain tissue is reduced when the conversion of tyrosine to L-dopa is blocked. L-Dopa, the precursor of dopamine, can cross the blood-brain barrier and undergo conversion to dopamine, restoring neurotransmission ⁵¹⁾. Good yields of L-dopa can be extracted from Mucuna pruriens seeds with EtOH-H2O (1:1), using ascorbic acid as a protector ⁵²⁾. An n-propanol extract of Mucuna pruriens seeds yields the highest response in neuroprotective testing involving the growth and survival of DA neurons in culture. Interestingly, n-propanol extracts, which contain a negligible amount of L-dopa, have shown significant neuroprotective activity, suggesting that a whole extract of Mucuna pruriens seeds could be superior to pure L-dopa with regard to the treatment of parkinsonism.

Anti-diabetic effect of Mucuna pruriens seeds

Using a combination of chromatographic and NMR techniques, the presence of d-chiro-inositol and its two galacto-derivatives, O-α-d-galactopyranosil-(1→2)-d-chiro-inositol (FP1) and O-α-d-galactopyranosil-(1→6)-O-α-d-galactopyranosil-(1→2)-D-chiro-inositol (FP2), was demonstrated in Mucuna pruriens seeds ⁵³⁾. Galactopyranosyl d-chiro-inositols are relatively rare and have been isolated recently from the seeds of certain plants; they constitute a minor component of the sucrose fraction of Glycine max (Fabaceae) and lupins, and a major component of Fagopyrum esculentum (Polygonaceae) ⁵⁴⁾. Although usually ignored in phytochemical analyses conducted for dietary purposes, the presence of these cyclitols is of interest due to the insulin-mimetic effect of d-chiro-inositol, which constitutes a novel signaling system for the control of glucose metabolism ⁵⁵⁾. According to Akhtar et al., ⁵⁶⁾, Mucuna pruriens seeds used at a dose of 500 mg/kg reduced plasma glucose levels. These and other data demonstrated that the amount of seeds necessary to obtain a significant anti-diabetic effect contain a total of approximately 7 mg of d-chiro-inositol (including both free, and that derived from the hydrolysis of FP1 and FP2). The anti-diabetic properties of Mucuna pruriens seed EtOH/H2O 1:1 extract are most likely due to d-chiro-inositol and its galacto-derivatives.

Anti-oxidant activity of Mucuna pruriens

Free radicals that have one or more unpaired electrons are produced during normal and pathological cell metabolism. Reactive oxygen species (ROS) react readily with free radicals to become radicals themselves. Anti-oxidants provide protection to living organisms from damage caused by uncontrolled production of reactive oxygen species (ROS) and concomitant lipid peroxidation, protein damage and DNA strand breakage. Several substances from natural sources have been shown to contain anti-oxidants and are under study. Anti-oxidant compounds such as phenolic acids, polyphenols, and flavonoids, scavenge free radicals such as peroxide, hydroperoxide or lipid peroxyl, and thus inhibit oxidative mechanisms. Polyphenols are important phytochemicals due to their free radical scavenging and in vivo biological activities ⁵⁷⁾; the total polyphenolic content has been tested using Folin-Ciocalteau reagent. Flavonoids are simple phenolic compounds that have been reported to possess a wide spectrum of biochemical properties, including anti-oxidant, anti-mutagenic and anti-carcinogenic activity ⁵⁸⁾. The hydrogen donating ability of the methanol extract of Mucuna pruriens was measured in the presence of 1,1-diphenyl-2-picryl-hydrazyl (DPPH) radical. In a recent study, Kottai Muthu et al. ⁵⁹⁾ found that ethylacetate and methanolic extract of whole Mucuna pruriens plant (MEMP), which contains large amounts of phenolic compounds, exhibits high anti-oxidant and free radical scavenging activities. These in vitro assays indicate that this plant extract is a significant source of natural anti-oxidant, which may be useful in preventing various oxidative stresses. It has been reported ⁶⁰⁾ that methanolic extracts of Mucuna pruriens leaves have numerous biochemical and physiological activities, and contain pharmaceutically valuable compounds.

Mucuna pruriens for skin treatments

The skin is one of the main targets of several exogenous insults such as UV radiation, O3, and cigarette smoke, and all of these exert toxicity via the induction of oxidative stress ⁶¹⁾. Several skin pathologies, such as psoriasis, dermatitis, and eczema, are related to increased oxidative stress and reactive oxygen species (ROS) production ⁶²⁾ and research investigating novel natural compounds with anti-oxidant proprieties is an expanding field. As mentioned above, certain plant-derived compounds have been an important source of traditional treatments for various diseases, and have received considerable attention in more recent years due to their numerous pharmacological proprieties.

Recent preliminary studies from our group have shown that human keratinocytes treated with a methanolic extract from Mucuna pruriens leaves exhibit downregulation of total protein expression. In addition, treatment with Mucuna pruriens significantly decreased the baseline levels of 4HNE present in human keratinocytes ⁶³⁾. This preliminary study suggests that evaluating the effect that topical Mucuna pruriens methanolic extract treatment may have on skin diseases would be worthwhile, as would further work aimed at clarifying the mechanisms involved in such effects.

Mucuna pruriens dosage

Based on the small data from a 2017 randomized controlled trial ⁶⁴⁾ of 18 patients with advanced Parkinson’s disease found that Mucuna pruriens powder, at both high dose at 17.5 mg/kg body weight and low dose at 12.5 mg/kg body weight, is as effective and safe as levodopa/benserazide.

When compared to levodopa+carbidopa, Mucuna pruriens powder low dose at 12.5 mg/kg body weight showed similar motor response with fewer dyskinesias and side effects, while Mucuna pruriens powder at high dose at 17.5 mg/kg body weight induced greater motor improvement at 90 and 180 minutes, longer ON duration, and fewer dyskinesias. Mucuna pruriens powder at high dose at 17.5 mg/kg body weight induced less side effects than levodopa+carbidopa and levodopa. No differences in cardiovascular response were recorded.

Mucuna pruriens side effects

Side effects most commonly occurred within 30–45 minutes after treatment administration and lasted <15 minutes, except for 4 patients, who reported side effects lasting >90 minutes after levodopa ⁶⁵⁾. Despite similar levodopa dose, levodopa was associated with more frequent side effects than Mucuna pruriens powder at high dose at 17.5 mg/kg body weight, and it was the only treatment associated with prolonged side effects. There was no difference among the active treatments in terms of change in blood pressure and heart rate between off and on state.

Levodopa side effects

Along with its needed effects, a medicine may cause some unwanted effects. Although not all of these side effects may occur, if they do occur they may need medical attention.

Check with your doctor as soon as possible if any of the following side effects occur:

More common

• abnormal thinking: holding false beliefs that cannot be changed by fact
• agitation
• anxiety
• clenching or grinding of teeth
• clumsiness or unsteadiness
• confusion
• difficulty swallowing
• dizziness
• excessive watering of mouth
• false sense of well being
• feeling faint
• general feeling of discomfort or illness
• hallucinations (seeing, hearing, or feeling things that are not there)
• hand tremor, increased
• nausea or vomiting
• numbness
• unusual and uncontrolled movements of the body, including the face, tongue, arms, hands, head, and upper body
• unusual tiredness or weakness

Less common

• blurred vision
• difficult urination
• difficulty opening mouth
• dilated (large) pupils
• dizziness or lightheadedness when getting up from a lying or sitting position
• double vision
• fast, irregular, or pounding heartbeat
• hot flashes
• increased blinking or spasm of eyelids
• loss of bladder control
• mental depression
• other mood or mental changes
• skin rash
• unusual weight gain or loss

Rare

• back or leg pain
• bloody or black tarry stools
• chills
• convulsions (seizures)
• fever
• high blood pressure
• inability to move eyes
• loss of appetite
• pain, tenderness, or swelling of foot or leg
• pale skin
• prolonged, painful, inappropriate penile erection
• sore throat
• stomach pain
• swelling of face
• swelling of feet or lower legs
• vomiting of blood or material that looks like coffee grounds

Some side effects may occur that usually do not need medical attention. These side effects may go away during treatment as your body adjusts to the medicine. Also, your health care professional may be able to tell you about ways to prevent or reduce some of these side effects. Check with your health care professional if any of the following side effects continue or are bothersome or if you have any questions about them:

More common

• abdominal pain
• dryness of mouth
• loss of appetite
• nightmares
• passing gas

Less common

• constipation
• diarrhea
• flushing of skin
• headache
• hiccups
• increased sweating
• muscle twitching
• trouble in sleeping

Levodopa may sometimes cause the urine, saliva, and sweat to be darker in color than usual. The urine may at first be reddish, then turn to nearly black after being exposed to air. Some bathroom cleaning products will produce a similar effect when in contact with urine containing levodopa. This is to be expected during treatment with levodopa. Also, levodopa may cause a bitter taste, or a burning sensation of the tongue.

Other side effects not listed may also occur in some patients. If you notice any other effects, check with your healthcare professional.

Call your doctor for medical advice about side effects.

Nervous system side effects

Nervous system side effects most frequently reported have included involuntary movements and mental status changes (in as many as 50% of treated patients on long-term therapy). The types of involuntary movements due to levodopa have been characterized as choreiform, dystonic and dyskinetic. Fluctuations in motor function occur frequently and often increase as the duration of therapy increases.

Choreiform movements due to levodopa therapy may occur in as many as 80% of patients treated for one year and frequently involve facial grimacing, exaggerated chewing, and twisting and protrusion of the tongue.

Several types of motor fluctuations may occur and result in “bradykinetic episodes”. Some motor fluctuations are related to the timing of levodopa dosage administration. For example, patients may experience “peak of the dose dyskinesia” and a wearing-off effect called “end of the dose akinesia”. The “wearing-off effect may result in early morning dystonia. Such motor fluctuations may be managed by increasing the frequency of dosage administration and decreasing the dose administered to achieve a smoother therapeutic effect.

Other motor fluctuations are not related to the timing of dose administration. Such fluctuations are characterized by sudden loss of levodopa effect which may last for minutes to hours and result in akinesia followed by a sudden return of levodopa effect. These “on-off” fluctuations may occur many times per day. “On-off” fluctuations may respond to more frequent dose administration.

Finally, akinesia paridoxica is a sudden episode of akinesia which occurs as patients begin to walk. Akinesia paridoxica frequently results in falls and often responds to levodopa dose reductions.

Other adverse nervous system effects due to levodopa include myoclonus, sleep disturbances (including insomnia, daytime somnolence, altered dreams and episodic nocturnal myoclonus), Meige’s syndrome (blepharospasm-oromandibular dystonia) and ocular dyskinesia. In addition, the orofacial movements induced by levodopa have occasionally been reported to cause severe dental erosion.

Some investigators have suggested that levodopa may cause brain dysfunction and may have negative effects on cognitive performance. Levodopa “drug holidays” have been proposed by some investigators as potentially beneficial (perhaps by causing dopamine receptor resensitization). However, the therapeutic value of these drug holidays is controversial.

Gastrointestinal side effects

Exacerbation of preexisting stomach ulcer disease with severe upper gastrointestinal bleeding has been reported.

Gastrointestinal side effects most commonly reported have included nausea and vomiting. Anorexia and gastrointestinal hemorrhage have been reported rarely.

Psychiatric side effects

Some authors have suggested that clozapine may be useful in the management of levodopa-induced psychotic symptoms.

Other investigators have suggested that levodopa may induce alterations in the noradrenergic systems of the CNS which may lead to panic attacks.

Psychiatric side effects have included hallucinations (particularly visual hallucinations), psychosis, confusion, anxiety, mania, hypomania, depression, rapid mood cycling, nightmares, and hypersexuality.

Neuroleptic malignant syndrome

Fever, altered consciousness, autonomic dysfunction and muscle rigidity are the hallmarks of the neuroleptic malignant syndrome. The neuroleptic malignant syndrome (NMS) is associated with a case fatality rate of about 20%. If withdrawal of dopaminergic therapy is suspected as the cause of NMS (neuroleptic malignant syndrome), dopaminergic therapy should be restarted. If a neuroleptic agent is suspected as the cause, the neuroleptic agent should be immediately discontinued. For patients with NMS (neuroleptic malignant syndrome) suspected to be due to neuroleptic therapy, consideration should be given to dantrolene (or bromocriptine) administration. Intensive monitoring and supportive care are indicated for all patients with NMS (neuroleptic malignant syndrome).

Sudden discontinuation or rapid tapering of levodopa therapy may result in acute worsening of parkinsonism or less frequently, in a syndrome resembling the neuroleptic malignant syndrome. Cases of psychologic levodopa addiction have also been reported rarely.

Cardiovascular side effects

Some authors have reported marked hemodynamic and clinical improvements in patients with congestive heart failure treated with oral levodopa. However, at least one author has reported marked hemodynamic deterioration following such treatment.

Cardiovascular side effects have included hypotension and syncope. Arrhythmias have also been reported rarely.

Dermatologic side effects

Dermatologic side effects have included a number of cases of malignant melanoma in patients taking levodopa for Parkinson’s Disease. Additionally, several cases of maculopapular skin rashes have been reported in patients taking levodopa-containing drugs.

Despite reports of melanoma occurring in levodopa-treated patients, some authors have suggested that a causal association is tenuous and other authors have suggested that levodopa may have an antitumor effect on melanoma. Nevertheless, the manufacturers of levodopa-containing drugs report that either the history of melanoma or the presence of suspicious skin lesions is a contraindication for the use of levodopa-containing drugs.

Immunologic side effects

Immunologic side effects have included rare reports of a lupus-like syndrome.

Hematologic side effects

Hematologic side effects reported rarely have included severe hemolytic and nonhemolytic anemias.

Respiratory side effects

Respiratory side effects have included dyskinesias (occasionally of life-threatening severity).

Liver side effects

Hepatic side effects have included rare cases of asterixis (without abnormalities of liver function tests). The manufacturer of levodopa-containing products reports that abnormal liver function tests may occur.

Endocrine side effects

Endocrine side effects have included elevated urinary vanillylmandelic acid levels which have occasionally led to confusion concerning the diagnosis of pheochromocytoma.

Kidney side effects

Renal side effects have included hypokalemia and hyponatremia. Chronic administration of levodopa may also slightly but significantly increase BUN without changes in the glomerular filtration rate.

What is maral root

Maral root is also known as Rhaponticum carthamoides or Russian leuzea is a member of the Asteraceae family, is a perennial, herbaceous species naturally growing in the mountains of South Siberia, Middle Asia, and Mongolia ¹⁾. Maral root has been used for centuries in Siberian (eastern parts of Russia) folk medicine as a stimulant, mostly in the case of overstrain and weakness after illness ²⁾. The root and rhizome extracts of Rhaponticum carthamoides possess a wide range of biological activities, including adaptogenic, antioxidant, cardioprotective, immunomodulatory, antihyperlipidemic, antihyperglycemic, and antimicrobial effects ³⁾. These pharmacological properties are attributed to the presence of a variety of secondary metabolites including triterpenoids, polyacetylenes, sesquiterpene lactones, phenolic acids, flavonoids, and ecdysteroids with 20-hydroxyecdysone as the principal component ⁴⁾.

Figure 1. Rhaponticum carthamoides (Maral root)

Rhaponticum carthamoides extracts from roots and rhizomes of this species are used in various dietary supplements or nutraceutical preparations to increase energy level and eliminate physical weakness or for recovery after surgery ⁵⁾. Rhaponticum carthamoides is also known to have adaptogenic, immunomodulatory, anticarcinogenic, antioxidant, and antimicrobial activities ⁶⁾. The antiradical effects of the aerial part of Rhaponticum carthamoides have already been evaluated by the most common radical-scavenging assays based on 2,2-diphenyl-1-picrylhydrazyl (DPPH) ⁷⁾, 2,2′-azinobis(3-ethylbenzothiazoline-6-sulfonic acid) (ABTS) assays ⁸⁾ and ferric reducing antioxidant power (FRAP) tests ⁹⁾. The important antioxidant compounds of this plant are polyphenolic compounds such as flavonoids (e.g., quercetin, quercetagetin, luteolin, patuletin, and kaempferol) and phenolic acids (e.g., caffeic, chlorogenic, and ferulic acids and caffeoylquinic acid derivatives) ¹⁰⁾.

Table 1. Bioactive compounds from maral root extracts – quantification of polyphenols and 20-hydroxyecdysone

Ecdysterones (also known as ectysterone, 20 Beta-Hydroxyecdysterone, turkesterone, ponasterone, ecdysone, or ecdystene) are naturally derived phytoecdysteroids (i.e., insect hormones) ¹²⁾. They are typically extracted from the herbs Rhaponticum carthamoides, Leuza rhaptonticum sp., or Cyanotis vaga. They can also be found in high concentrations in the herb Suma (also known as Brazilian Ginseng or Pfaffia). Research from Russia and Czechoslovakia conducted over the last 30 years indicates that ecdysterones may possess some potentially beneficial physiological effects in insects and animals ¹³⁾. However, since most of the data on ecdysterones have been published in obscure journals, results are difficult to interpret. Wilborn and coworkers ¹⁴⁾ gave resistance trained males 200 mg of 20-hydroxyecdysone per day during 8-weeks of resistance training. It was reported that the 20-hydroxyecdysone supplementation had no effect on fat free mass or anabolic/catabolic hormone status ¹⁵⁾. Due to the findings of this well controlled study in humans, ecdysterone supplementation at a dosage of 200 mg per day appears to be ineffective in terms of improving lean muscle mass ¹⁶⁾. While future studies may find some ergogenic value of ecdysterones, it is the view of the International Society of Sports Nutrition that it is too early to tell whether phytoecdysteroids serve as a safe and effective nutritional supplement for athletes.

The principal bioactive constituents of the whole Rhaponticum carthamoides plant are ecdysteroids, flavonoids, and phenolic acids. The aerial parts also contain sesquiterpene lactones of the guaianolide type, while the roots contain thiophene-based polyines ¹⁷⁾. There have been two recent studies about antioxidant properties of Rhaponticum carthamoides. The first study dealt with the antioxidant screening of 12 medical plants and concludes that the extract of Rhaponticum carthamoides possesses high radical scavenging activity ¹⁸⁾. The second study identifies 7 natural compounds of Rhaponticum carthamoides by means of on-line LC-DAD-SPE-NMR system. Nevertheless, incomplete evaluation of the radical scavenging or antioxidant activity of Rhaponticum carthamoides extracts or pure compounds has occured ¹⁹⁾. The results of DPPH and FRAP tests evaluated 6-hydroxykaempferol-7-O-(6″-O-acetyl-β-D-glucopyranoside) as the most antioxidant active compound. The antioxidant activity of maral roots is currently under investigation.

What is GABA

GABA is short for Gamma-Aminobutyric Acid, which is a naturally occurring inhibitory neurotransmitter with central nervous system (CNS) inhibitory activity. GABA acts by binding to specific transmembrane receptors in the plasma membrane of both presynaptic and postsynaptic neurons in your brain. This binding causes the opening of ion channels to allow either the flow of negatively-charged chloride ions into the cell or positively-charged potassium ions out of the cell. This will typically result in a negative change in the transmembrane potential, usually causing hyperpolarization. Three general classes of GABA receptor are known ¹⁾. These include GABA-A and GABA-C ionotropic receptors, which are ion channels themselves, and GABA-B metabotropic receptors, which are G protein-coupled receptors that open ion channels via intermediaries known as G proteins ²⁾. Activation of the GABA-B receptor by GABA causes neuronal membrane hyperpolarization and a resultant inhibition of neurotransmitter release. In addition to binding sites for GABA, the GABA-A receptor has binding sites for benzodiazepines, barbiturates, and neurosteroids. GABA-A receptors are coupled to chloride ion channels. Therefore, activation of the GABA-A receptor induces increased inward chloride ion flux, resulting in membrane hyperpolarization and neuronal inhibition ³⁾. After release into the synapse, free GABA that does not bind to either the GABA-A or GABA-B receptor complexes can be taken up by neurons and glial cells. Four different GABA membrane transporter proteins (GAT-1, GAT-2, GAT-3, and BGT-1), which differ in their distribution in the central nervous system (CNS), are believed to mediate the uptake of synaptic GABA into neurons and glial cells. The GABA-A receptor subtype regulates neuronal excitability and rapid changes in fear arousal, such as anxiety, panic, and the acute stress response ⁴⁾. Drugs that stimulate GABA-A receptors, such as the benzodiazepines and barbiturates, have anxiolytic and anti-seizure effects via GABA-A-mediated reduction of neuronal excitability, which effectively raises the seizure threshold. GABA-A antagonists (blockers) produce convulsions in animals and there is decreased GABA-A receptor binding in a positron emission tomography (PET) study of patients with panic disorder. Neurons that produce GABA as their output are called GABAergic neurons and have chiefly inhibitory action at receptors in the vertebrate. Medium spiny neurons are a typical example of inhibitory CNS GABAergic cells. GABA is known for its analgesic effects, anti-anxiety, and hypotensive activity. GABA has also been shown to have excitatory roles in the vertebrate, most notably in the developing cortex.

Although GABA usually induces hyperpolarization in adult neurons, GABA has also been shown to exert depolarizing responses in the immature CNS structures and CNS tumors ⁵⁾. In particular, GABA increased the proliferation of immature cerebellar granule cells through the activation of GABA-A receptors and voltage-dependent calcium channels ⁶⁾. Takehara et al. ⁷⁾ reported that GABA stimulated pancreatic cancer growth through GABRP (GABA-A receptor pi subunit) by increasing intracellular Ca2+ levels and activating the mitogen-activated protein kinase/extracellular signal-regulated kinase cascade. Also, Minuk et al. ⁸⁾ reported that human hepatocellular carcinoma tissues were depolarized compared with adjacent non-tumor tissues. From the results above, it was deduced that GABA may promote the malignant liver cell lines HepG2 cell proliferation through gamma-aminobutyric acid A receptor θ subunit (GABRQ) by voltage-dependent calcium channels. Interestingly, GABA inhibited the growth of the gamma-aminobutyric acid A receptor θ subunit (GABRQ)-knockdown malignant liver cell lines HepG2 cells. This indicates that GABA activates some other receptors to inhibit the proliferation without gamma-aminobutyric acid A receptor θ subunit (GABRQ), which is identical to some previous reports ⁹⁾. Hepatocellular carcinoma tissues have increased gamma-aminobutyric acid A receptor θ subunit (GABRQ) receptor expression ¹⁰⁾. Knockdown of gamma-aminobutyric acid A receptor θ subunit (GABRQ) expression in receptor-expressing malignant hepatocytes results in attenuated in vitro and in vivo tumor growth ¹¹⁾. Moreover, GABA promotes hepatocyte proliferation through GABRQ. These findings highlight the importance of elucidating the role of GABAergic activity in the pathogenesis of hepatocellular carcinoma. They also raise the potential for new therapeutic and diagnostic approaches to human hepatocellular carcinoma.

Figure 1. GABA (Gamma-Aminobutyric Acid)

GABA dietary sources

GABA is found ubiquitously among plants (Figure 2), where GABA can be primarily synthesized from glutamic acid via glutamate decarboxylase enzyme. Levels of GABA were demonstrated to increase in response to biotic and abiotic stresses, such as drought, the presence of salt, wounds, hypoxia, infection, soaking, and germination ¹²⁾. In particular, sprouts of Lupinus angustifolius L. (that is, lupin) ¹³⁾, Vigna angularis W. (that is, adzuki bean) ¹⁴⁾ and other germinating edible beans, such as Glycine max L. (that is, soya bean) ¹⁵⁾, common bean, and pea ¹⁶⁾, were reported to increase GABA content when compared to their raw beans. Furthermore, grains of the Gramineae family, such as Avena nuda L. (that is, oat) ¹⁷⁾, Triticum aestivum L. (that is, wheat) ¹⁸⁾, Hordeum vulgare L. (that is, barley) ¹⁹⁾, and many species of the Oryza genus (for example, white, black, brown, and red rice) ²⁰⁾ can also significantly accumulate GABA. Sprouts of Fagopyrum esculentum M. (that is, buckwheat) ²¹⁾ and the fruits of tomato also contain a substantial amount of this amino acid during the mature green stage ²²⁾.

Food technologies and molecular engineering are employed to synthesize GABA through enzymatic or whole-cell biocatalysis, microbial fermentation (for example, GABA soya yogurt ²³⁾, black raspberry juice ²⁴⁾, and chemical synthesis ²⁵⁾. Some authors found one of the highest contents on GABA to be 414 nmol/g of dry weight in raw spinach, followed by Solanum tuberosum L. (that is, potato), Ipomoea batatas L. (that is, sweet potato), and Brassica oleracea L. (that is, cruciferous such as kale and broccoli). Mushrooms, such as Lentinula edodes B. (that is, shiitake), and nuts of Castanea genus (that is, chestnut) also showed a significant amount of GABA ²⁶⁾. Among the many types of Chinese teas, the highest content was found in white tea ²⁷⁾. GABA content was found in mistletoe ²⁸⁾, but also in Phytolacca americana L. (that is, pokeroot) ²⁹⁾, Valeriana officinalis L. (that is, valerian), Angelica archangelica L.(that is, wild celery), Hypericum perforatum L. (that is, St John’s wort), Hieracium pilosella L. (that is, mouse-ear hawkweed), and Passiflora incarnata L. (that is, maypop) ³⁰⁾, the latter being used for the relief of mild symptoms of mental stress and as a sleep aid.

Moreover, the benefit from the consumption of GABA-containing vegetables showed the importance of dietary GABA on the sympathetic nerve activity ³¹⁾. Conversely, there is still discordance over the alleged GABA capacity to cross the blood-brain barrier ³²⁾.

Figure 2. GABA dietary sources

GABA Synthesis

GABA synthesis occurs from glutamate or L-glutamate (the principal excitatory neurotransmitter in the brain) via the decarboxylation of L-glutamate by the enzyme L-glutamic acid decarboxylase (GAD)—a single-step, irreversible reaction dependent on the availability of the cofactor pyridoxal-50-phosphate (a vitamer of vitamin B6) ³⁴⁾. It is worth noting that this involves converting the principal excitatory neurotransmitter glutamate into GABA the principal inhibitory one. Gamma-aminobutyric acid (GABA) plays a role in regulating neuronal excitability by binding to its receptors, GABA-A and GABA-B, and thereby causing ion channel opening, hyperpolarization and eventually inhibition of neurotransmission.

Two major isoforms of the enzyme L-glutamic acid decarboxylase (GAD) exist—a 65 kDa isoform (GAD65) and a 67 kDa isoform (GAD67); GAD65 is the major isoform of GAD expressed in the mammalian brain ³⁵⁾, localized primarily to the axon terminals of synaptosomes and interacting readily with the plasma membrane, whereas GAD67 is more widely distributed in the cytosol of cells ³⁶⁾. The differential distribution of the two GAD isoforms corresponds well with the presence of two pools of intracellular GABA—one of which is found in vesicles and the other in the cytosol, and which are released by different mechanisms ³⁷⁾. It has thus been suggested that GAD65, being localized in the synaptic bouton, plays a role in the synthesis of GABA released via a vesicular mechanism ³⁸⁾, whereas GAD67 likely mediates the synthesis of the cytoplasmic pool of GABA ³⁹⁾.

What does GABA do?

GABA (gamma-aminobutyric acid) is the major inhibitory neurotransmitter in the brain ⁴⁰⁾ and is produced from glutamate by l-glutamic acid decarboxylase (GAD) within GABAergic neurons ⁴¹⁾. GABA is then metabolized to succinic acid semialdehyde by GABA transaminase and then to succinate, mainly within astrocytic mitochondria ⁴²⁾. GABA is needed for normal brain function, synaptic plasticity, cortical adaptation and reorganization ⁴³⁾.

GABA is crucially important in the regulation of responsiveness and excitability in human cortical networks ⁴⁴⁾ and in the synchronization of cortical neuronal signaling activity by networks of cortical interneurons ⁴⁵⁾. The ubiquity of GABAergic regulation in the CNS gives this neurotransmitter a central role in a very wide range of physiological and biochemical processes—GABAergic control is involved in the regulation of cognition ⁴⁶⁾, memory and learning ⁴⁷⁾, motor function ⁴⁸⁾, circadian rhythms ⁴⁹⁾, neural development ⁵⁰⁾, adult neurogenesis ⁵¹⁾, and sexual maturation⁵²⁾. Dysfunction in GABAergic signaling is known to be a central factor in the pathogenesis of several neurological disorders, with the role of GABA in epilepsy and the maintenance of the inhibitory-excitatory (E/I) balance in the human cortex being the subject of significant topic in research ⁵³⁾. The contribution of GABAergic dysfunction to
disorders such as epilepsy [genetic epilepsies] ⁵⁴⁾, Alzheimer’s disease ⁵⁵⁾, major depressive disorder ⁵⁶⁾, anxiety ⁵⁷⁾, autism ⁵⁸⁾, schizophrenia ⁵⁹⁾ and bipolar disorder ⁶⁰⁾ is also known or suspected, with many lines of evidence pointing to the underlying contribution of defects in the signaling system ⁶¹⁾. GABAergic inhibition may be one of the mechanisms involved in use-dependent plasticity in the intact human motor cortex ⁶²⁾. Changes in GABA concentration in the sensorimotor cortex during motor learning have been demonstrated ⁶³⁾. One pilot study in relapsing-remitting multiple sclerosis (MS) ⁶⁴⁾ found that reduced motor performance correlated with increased GABA levels in the sensorimotor cortex. The increased GABA concentration was also associated with increased motor activation on functional MRI. Despite limitations, these in vivo results suggest that cortical reorganization occurring in the sensorimotor cortex in patients with relapsing-remitting multiple sclerosis, as reflected by increased functional MRI response, is linked with increased GABA levels, and is a possible compensatory mechanism that maintains motor function ⁶⁵⁾. The observed reduced GABA levels in the hippocampus and sensorimotor cortex in patients with secondary progressive multiple sclerosis when compared with healthy controls raises the possibility that GABA may be a marker of neurodegeneration in the brain. The reduction in GABA levels may reflect a combination of reduced GABA receptor levels and decreased density of inhibitory interneuron processes in the motor cortex in patients with progressive multiple sclerosis, which have been described by a previous histological study ⁶⁶⁾. Lower GABA levels in the sensorimotor cortex of multiple sclerosis patients are associated with reduced motor performance. These findings raise the possibility that altered GABA neurotransmission may be a marker of neurodegeneration, but it may also suggest that GABA is a mechanism of neurodegeneration in progressive multiple sclerosis patients. Thus, the GABAergic system has long been a major target in the development of treatment strategies for these conditions. Following is a brief description of the major components of the GABAergic system (summarized in Figure 3).

Figure 3. GABA signaling system

Footnotes: An overview of the γ-aminobutyric acid (GABA) signaling system. The schematic diagram represents a GABAergic synapse and depicts the key aspects of GABAergic signal transduction. GABA is synthesized in the pre-synaptic terminal from glutamate by glutamic acid decarboxylase (GAD). GABA is then recruited into synaptic vesicles via the action of vesicular GABA transporter (vGAT). Following membrane depolarization, GABA is released into the synapse and can bind to either ionotropic GABAA receptors (GABAAR) or metabotropic GABAB receptors (GABABR) on the postsynaptic membrane, resulting in inhibition of the post-synaptic neuron. Released GABA is cleared from the synapse by membrane-bound GABA transporters (GATs), localized to neurons and astrocytes. In astrocytes, GABA is recycled into synaptic vesicles or taken up by mitochondria, where it is metabolized by GABA transaminase (GABA-T) to glutamine for neuronal uptake.

Drugs that act as agonists of GABA receptors (known as GABA analogs or GABAergic drugs), or increase the available amount of GABA typically have relaxing, anti-anxiety, and anti-convulsive effects. GABA is found to be deficient in cerebrospinal fluid (CSF) and the brain in many studies of experimental and human epilepsy. Benzodiazepines (such as Valium) are useful in status epilepticus because they act on GABA receptors. GABA increases in the brain after administration of many seizure medications. Hence, GABA is clearly an antiepileptic nutrient.

Central nervous system (CNS) depressants, a category that includes tranquilizers, sedatives, and hypnotics, are substances that can slow brain activity. This property makes them useful for treating anxiety and sleep disorders. Most central nervous system (CNS) depressants act on the brain by increasing activity at receptors for the inhibitory neurotransmitter GABA (gamma-aminobutyric acid). Although the different classes of depressants work in unique ways, it is through their ability to increase GABA signaling—thereby increasing inhibition of brain activity—that they produce a drowsy or calming effect that is medically beneficial to those suffering from anxiety or sleep disorders ⁶⁷⁾.

The following are among the medications commonly prescribed for these purposes ⁶⁸⁾:

• Benzodiazepines, such as diazepam (Valium), clonazepam (Klonopin), and alprazolam (Xanax), are sometimes prescribed to treat anxiety, acute stress reactions, and panic attacks. Clonazepam may also be prescribed to treat seizure disorders. The more sedating benzodiazepines, such as triazolam (Halcion) and estazolam (Prosom) are prescribed for short-term treatment of sleep disorders. Usually, benzodiazepines are not prescribed for long-term use because of the high risk for developing tolerance, dependence, or addiction.
• Non-benzodiazepine sleep medications, such as zolpidem (Ambien), eszopiclone (Lunesta), and zaleplon (Sonata), known as z-drugs, have a different chemical structure but act on the same GABA type A receptors in the brain as benzodiazepines. They are thought to have fewer side effects and less risk of dependence than benzodiazepines.
• Barbiturates, such as mephobarbital (Mebaral), phenobarbital (Luminal), and pentobarbital sodium (Nembutal), are used less frequently to reduce anxiety or to help with sleep problems because of their higher risk of overdose compared to benzodiazepines. However, they are still used in surgical procedures and to treat seizure disorders.

Inhibitors of GAM metabolism can also produce convulsions. Spasticity and involuntary movement syndromes, such as Parkinson’s, Friedreich’s ataxia, tardive dyskinesia, and Huntington’s chorea, are all marked by low GABA when amino acid levels are studied. Trials of 2 to 3 g of GABA given orally have been effective in various epilepsy and spasticity syndromes. Agents that elevate GABA are also useful in lowering hypertension. Three grams orally have been effective in controlling blood pressure. GABA is decreased in various encephalopathies. GABA can reduce appetite and is decreased in hypoglycemics. GABA reduces blood sugar in diabetics. Chronic brain syndromes can also be marked by deficiencies of GABA. Vitamin B6, manganese, taurine, and lysine can increase both GABA synthesis and effects, while aspartic acid and glutamic acid probably inhibit GABA effects.

Low plasma GABA has been reported in some depressed patients and may be a useful trait marker for mood disorders. GABA has an important role in embryonic development, especially facial development, as substantiated by the association of a cleft palate in transgenic mice deficient in GAD67 (glutamate decarboxylase). A recent Japanese population study reported linkage in patients with a nonsyndromic cleft lip with or without a cleft palate and specific GAD67 haplotypes ⁶⁹⁾.

Unusually high levels of GABA (especially in the brain) can be toxic and GABA can function as both a neurotoxin and a metabotoxin. A neurotoxin is a compound that damages the brain and/or nerve tissue. A metabotoxin is an endogenously produced metabolite that causes adverse health effects at chronically high levels. Chronically high levels of GABA are associated with at least five inborn errors of metabolism, including D-2-hydroxyglutaric aciduria, 4-hydroxybutyric aciduria/succinic semialdehyde dehydrogenase deficiency, GABA-transaminase deficiency, homocarnosinosis, and hyper beta-alaninemia ⁷⁰⁾. Nearly all of these conditions are associated with seizures, hypotonia, intellectual deficits, macrocephaly, encephalopathy, and other serious neurological or neuromuscular problems ⁷¹⁾. Increased levels of GABA seem to alter the function of the GABA-B receptor, which may play a role in the tonic-clonic seizures that are often seen in patients with the above disorders.

GABA Metabolism and Homeostasis

GABA metabolism in the brain occurs through a highly compartmentalized set of enzymatic processes. Neurotransmitter levels at GABAergic and glutamatergic synapses are largely maintained by astrocytes, through their mediation of the glutamate/GABA-glutamine cycle (summarized in Figure 2) ⁷²⁾. Cortical synapses are tightly enveloped by highly specialized astroglial processes ⁷³⁾, where GABA is taken up following synaptic release ⁷⁴⁾ and catabolized to succinate in a two-step reaction catalyzed by the mitochondrial enzymes GABA transaminase (GABA-T) and succinate semialdehyde dehydrogenase (SSADH). Succinate, being an intermediate component of the tricarboxylic acid (TCA) cycle, is subsequently converted to glutamine (Gln) by glutamine synthase, and glutamine (Gln) is then transported into neurons where it undergoes conversion to glutamate (Glu) ⁷⁵⁾. It has been estimated that GABA metabolism accounts for ~8–10% of the total flow through the neuronal tricarboxylic acid cycle ⁷⁶⁾. Most of this glutamate then undergoes conversion to glutamine (Gln) through the action of the strictly astrocyte-specific enzyme glutamine synthetase (GS) ⁷⁷⁾]. Glutamine is released by astrocytes and taken up by the closely apposed presynaptic neurons, where it can be re-converted to glutamate through the action of the predominantly neuronally localized enzyme phosphate-activated glutaminase (PAG) ⁷⁸⁾; this process is regulated by the availability of phosphorylated species such as ATP and GTP ⁷⁹⁾, by tricarboxylic acid cycle intermediates ⁸⁰⁾, by cyclic nucleotides such as cAMP and cGMP [86], and by the products of the catalytic reaction (glutamate and NH4) ⁸¹⁾, allowing for negative control of this process at a number of different levels. Glutamate is thus readily available for GABA synthesis by glutamic acid decarboxylase (GAD).

Figure 4. GABA metabolic pathway in the brain

Footnotes: Disorders involving the GABA catabolic pathway are GABA-T deficiency, succinic semi-aldehyde dehydrogenase (SSADH) deficiency and homocarnosinosis; all of these entities invoke neurological dysfunction. Succinic semi-aldehyde dehydrogenase (SSADH) deficiency is the most common, but has a heterogeneous, nonspecific phenotype. Enzymatic deficiency can be documented in SSADH and GABA-T deficiency. Homocarnosine is a dipeptide compound consisting of GABA and histidine.

Figure 5. GABA synthesis and catabolism in the brain

Abbreviations: αKGDH = α-ketoglutarate dehydrogenase; AAT = aspartate aminotransferase; CoA = coenzyme A; Cys = cysteine; GABA = γ-aminobutyric acid; GDH = glutamate dehydrogenase; GABA-T = GABA transaminase; GAD = glutamic acid dehydrogenase; GCL = γ-glutamyl cysteine ligase; Gln = glutamine; Glu = glutamyl; Gly = glycine; GSH = glutathione; GHB = γ-hydroxybutyric acid; GGT = γ-glutamyl transferase; GGCT = γ-glutamyl cyclotransferase; OPLAH = 5-oxoprolinase (adenosine triphosphate-hydrolyzing); SSADH = succinic semialdehyde dehydrogenase; SSAR, succinic semialdehyde reductase.

Mechanisms of GABA Transport and Synaptic Uptake

The GABAergic system plays an essential role in the fine temporal control of neuronal activity, at the level of individual neurons as well as larger neuronal populations. For this reason, the timing of receptor activation is important, and GABA levels in the extracellular compartment must be carefully regulated ⁸⁴⁾. The clearance of GABA from the synaptic cleft, and its reuptake into neurons and astrocytes following neurotransmission, occurs through high-affinity GABA uptake systems ⁸⁵⁾. GABA transport is mediated primarily by four GABA/Na+/Cl-symporters—in humans these are GABA transporter 1 (GAT1), GABA transporter 2 (GAT2), GABA transporter 3 (GAT3) and the betaine-GABA transporter (BGT1). Within neurons, GABA transport into synaptic vesicles is mediated by the vesicular GABA transporter (vGAT) ⁸⁶⁾. Functionally, the GABA transporters are responsible for the modulation of GABAergic inhibition by terminating the synaptic action of GABA and thus shaping the postsynaptic response to inhibitory presynaptic neurotransmitter release ⁸⁷⁾. The differing ionic and pharmacological sensitivities of the different GABA transporters, and their differing affinities for GABA transport, make this a very heterogeneous uptake system which can control inhibitory synaptic signaling in a number of ways ⁸⁸⁾. The GABA transporters are widely distributed throughout the mammalian central nervous system, with individual transporters having unique and sometimes overlapping regional distributions, mainly located on neuronal and glial cell membranes ⁸⁹⁾.

GABA transporter 1 (GAT1) is the most highly expressed GABA transporter in the mammalian cerebral cortex ⁹⁰⁾, and is generally considered to be the primary presynaptic neuronal GABA transporter. This transporter is also localized to astrocytic membranes at GABAergic synapses ⁹¹⁾. The extensive nature of GABA transporter 1 (GAT1) expression reflects its importance in regulating cortical excitability and information processing at synapses ⁹²⁾. GABA transporter 2 (GAT2) is primarily found in various tissues outside of the CNS (in particular in the proximal tubules of the kidney, in the heart, and in liver hepatocytes), but has a limited distribution in some regions of the brain and in the retina ⁹³⁾. GABA transporter 3 (GAT3) is primarily found in the nervous system, and is localized almost entirely to the processes of astrocytes within the cerebral cortex, indicating that this transporter is responsible for the uptake of GABA into astrocytes rather than neurons ⁹⁴⁾. Betaine-GABA transporter (BGT1) is primarily a transporter for betaine, and has a lower affinity for GABA than the aforementioned transporters. The distribution of betaine-GABA transporter (BGT1) in the mammalian brain is contentious, but some studies report that it is expressed by astrocytes at extrasynaptic sites, possibly suggesting a role in the regulation of tonic extracellular GABA levels.

GABA, Diseases, and Treatment

Increasing GABA in the brain has for years been the focus of drug development aiming to alleviate the severity of epileptic seizures ⁹⁵⁾. Initial studies examined the efficacy of administering GABA directly. One study reported a reduction in the amount of seizures in epileptic patients who were administered a very high dose of GABA (0.8 g/kg daily) ⁹⁶⁾. However, this result was found only in four out of twelve patients. Additionally, the patients in whom the administration of GABA did have an effect were children below the age of 15. This finding is in line with the suggestion that the blood–brain barrier (BBB) permeability to GABA decreases with age ⁹⁷⁾. Perhaps more importantly, GABA’s half-life is about 17 min in mice ⁹⁸⁾. If the half-life has a similar short duration in humans, direct administration of GABA is unsuitable as pharmacological treatment of epilepsy.

The GABA analog gabapentin was developed as an anti-epileptic drug. Gabapentin functions by modulating enzymes involved in GABA synthesis. It differs in chemical structure from GABA and its half-life is much longer ⁹⁹⁾. One proton magnetic resonance spectroscopy (¹H-MRS) study in humans has found that the administration of gabapentin increased brain GABA levels by 55.7% ¹⁰⁰⁾. Nonetheless, a study exploring the effects of gabapentin in both rat and human neocortical slice preparations suggests that there might be a considerable difference between rodents and humans in the effects on GABA levels: gabapentin was found to increase GABA concentrations by 13% in human neocortical slices, while having no significant effect in rat neocortical slices ¹⁰¹⁾.

Patients with Huntington’s disease also have reduced GABA levels in the brain ¹⁰²⁾, but administration of GABA to remedy this deficiency has shown mixed results with regards to the reduction of symptoms ¹⁰³⁾. Of course, that the administration of GABA does not consistently alter the symptoms in complex and multifaceted disorders such as epilepsy and Huntington’s disease, does not necessarily mean that GABA is unable to affect the brain ¹⁰⁴⁾.

GABA and Alzheimer’s disease

In the past few decades, many studies have implicated the disruption of cholinergic and glutamatergic neurotransmission in Alzheimer’s disease. Now increasing attention is also being paid to the role of GABAergic dysfunction in Alzheimer’s disease ¹⁰⁵⁾. Despite some controversy in the field, there is much evidence to suggest that GABAergic remodeling is a feature of Alzheimer’s disease, being potentially initiated at early stages of disease pathogenesis. There is evidence that alterations in various components of the GABAergic system, including GABA levels, glutamic acid decarboxylase (GAD) activity, GABA currents, and the distribution and subunit composition of GABARs and GABA transporters, might not be occurring simply as a compensatory mechanism in response to glutamate excitotoxicity. Indeed, some alterations might also be caused by the direct effect of Aβ. Thus, the Aβ-induced disruption of GABAergic inhibitory neurotransmission could represent a key mechanism whereby network activity is impaired in Alzheimer’s disease. In this manner, GABAergic remodeling may be involved in E/I balance disruptions that lead to early cognitive deterioration in the Alzheimer’s disease brain. A novel idea emerging from this body of research is the suggestion that the GABAergic system is an important factor in both the early and later stages of disease progression, and is not simply altered as a secondary pathological response. It is thus important to consider both direct and compensatory alterations in GABAergic activity in Alzheimer’s disease. Due to the limitations of previous studies and the inconsistency of previous results, the consequences of these alterations on neural network activity and behavior/cognition are not yet well understood. It is also important to take into account the huge translational gap between animal and in vitro models of Alzheimer’s disease and human clinical trials, and to consider the possibility that currently available Alzheimer’s disease models fail to capture key characteristics of the human disease.

Currently, the only Food and Drug Administration (FDA) approved drugs available to Alzheimer’s disease patients are those targeting either the cholinergic system (e.g. donepezil, tacrine, rivastigmine and galantamine) or the glutamatergic system (e.g. memantine) ¹⁰⁶⁾. None of these drugs are curative or disease-modifying, providing only temporary, symptomatic relief, and only to a subset of Alzheimer’s disease patients. As these drugs are only marginally effective, unable to prevent or reverse cognitive decline, and produce many unwanted side effects, there is an ongoing search for novel therapeutic targets ¹⁰⁷⁾.

Therefore, there is an urgent need to pursue further research in this area, to enhance our understanding of Alzheimer’s disease-associated alterations in the GABAergic system. Evidence for Alzheimer’s disease-associated GABAergic remodeling along with the failure of anti-glutamatergic and acetylcholinesterase inhibitor therapies to halt the progression of the disease could point to the GABAergic system as a promising therapeutic target for Alzheimer’s disease.

GABA supplement

Gamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the human cortex. In recent years it has become widely available as a food supplement. In Europe and the United States, GABA is considered a “food constituent” and a “dietary supplement,” respectively. As such, manufacturers are not required to provide evidence supporting the efficacy of their products as long as they make no claims with regards to potential benefits in relation to specific diseases or conditions. The food supplement version of GABA is widely available online. Although many consumers claim that they experience benefits from the use of these products, it is unclear whether these supplements confer benefits beyond a placebo effect ¹⁰⁸⁾. In recent years researchers have reported a number of placebo-controlled studies in which GABA was administered as a food supplement to healthy participants and participants with a history of acrophobia. One study found an increase in alpha waves in healthy participants and reduced levels of immunoglobulin A (IgA; an indicator of immune system functioning) in participants with a history of acrophobia when they were exposed to heights ¹⁰⁹⁾. However, the sample size for the second finding was very small (four participants per group). Another study reported reduced heart rate variability and salivary chromogranin A (CgA) during an arithmetic task compared to a control group after the administration of GABA-enriched chocolate ¹¹⁰⁾. A third study reported less salivary cortisol and CgA than a control group during a psychological stress-inducing arithmetic task. Additionally, participants who received 50 mg of GABA dissolved in a beverage reported less psychological fatigue after completion of the task ¹¹¹⁾. Finally, in a fourth study, participants were found to show a decrease in alpha waves over time while performing an arithmetic task. This decrease was smaller in the group that orally received GABA (100 mg) compared to a control group ¹¹²⁾. By way of comparison, one would have to eat 2.34 kg of uncooked spinach in order to consume a similar amount of GABA, and spinach is relatively rich in GABA compared to other foods ¹¹³⁾.

The results of these studies support the claims made by hundreds of consumers of GABA food supplement products and fit with a growing trend in which GABA is administered through everyday (natural) foods ¹¹⁴⁾. However, there are some caveats to consider. First, at least one of the authors in each of these four studies was affiliated with the company that produces the GABA supplement in question. However, a declaration of conflicting interests is lacking in three out of four of these studies. Second, the reported studies used “pharma-GABA,” which is produced for the Asian market through a fermentation process using a strain of lactic acid bacteria, Lactobacillus hilgardii K-3 ¹¹⁵⁾. Pharma-GABA has been approved by the FDA as a food ingredient ¹¹⁶⁾. While the manufacturer of pharma-GABA suggests that there are important differences with the synthetic GABA supplement sold online in Western countries, these differences refer to the production process and the occurrence of potentially harmful byproducts in synthetically produced GABA, and not to the chemical structure of the active compound GABA.

Currently, the mechanism of action behind these GABA supplements is unknown ¹¹⁷⁾. It has long been thought that GABA is unable to cross the blood–brain barrier (BBB), but the studies that have assessed this issue are often contradictory and range widely in their employed methods. Accordingly, future research needs to establish the effects of oral GABA administration on GABA levels in the human brain, for example using magnetic resonance spectroscopy. There is some evidence in favor of a calming effect of GABA food supplements, but most of this evidence was reported by researchers with a potential conflict of interest ¹¹⁸⁾.

A recent study by Steenbergen et al. (2015a) with human subjects has shown that the ingestion of synthetic GABA (800 mg) enhanced the ability of prioritized planned actions and inhibitory control ¹¹⁹⁾. However, in view of the lack of evidence with regards to GABA’s blood–brain barrier (BBB) permeability in humans, the mechanism through which GABA might have exerted these effects remains unclear. The same holds for the pharma-GABA studies that were discussed above: none of these effects exclude an indirect of GABA on the brain. The oral intake of these supplements may have exerted these effects through indirect pathways, for example through the enteric nervous system.

Enteric Nervous System Effects of GABA

The bidirectional signaling between the brain and the enteric nervous system is vital in maintaining homeostasis ¹²⁰⁾. Even though most research thus far has focused on the signaling from the brain to the gut, an increasing number of studies has explored the influence of the gut’s microbiota on the brain. For example, gut microbiota have been shown to improve mood and reduce anxiety in patients with chronic fatigue ¹²¹⁾. Similarly, oral intake of probiotics resulted in reduced urinary cortisol and perceived psychological stress ¹²²⁾ and reduced reactivity to sad mood ¹²³⁾ in healthy subjects.

It has been found that certain probiotic strains are able to produce GABA in vivo. Specifically, bacteria from the strains Lactobacillus and Bifidobacterium were effective at increasing GABA concentrations in the enteric nervous system ¹²⁴⁾. Indeed, both GABA and its receptors are widely distributed through the enteric nervous system ¹²⁵⁾. Additionally, there is considerable communication between the gut and the brain through the vagal nerve ¹²⁶⁾. This nerve consists, for the most part, of sensory nerve fibers that relay information about the state of bodily organs to the central nervous system ¹²⁷⁾.

A study in mice showed that the administration of Lactobacillus rhamnosus (JB-1) consistently modulated the mRNA expression of GABAAα2, GABAAα1, and GABAB1b receptor subunits ¹²⁸⁾, receptors commonly associated with anxiety-like behavior. Indeed, on a behavioral level the L. rhamnosus (JB-1)-fed mice were less anxious and displayed antidepressant-like behaviors in comparison with controls. Furthermore, the administration of these bacteria reduced the stress-induced elevation of corticosterone compared to the control mice. Importantly, none of these effects were present in mice that underwent vagotomy ¹²⁹⁾.

In humans, the stimulation of the vagus nerve through transcutaneous vagus nerve stimulation (tVNS) has been used to treat refractory epilepsy ¹³⁰⁾. This technique has been shown to affect norepinephrine, acetylcholine and GABA concentrations ¹³¹⁾. With regards to GABA, VNS seems to increase the level of free GABA in the cerebrospinal fluid ¹³²⁾. Similarly to the administration of synthetic GABA ¹³³⁾, active tVNS was found to enhance the ability of prioritizing and cascading different actions when performing a stop-change paradigm ¹³⁴⁾.

To summarize, bacteria from the Lactobacillus spp. strain contribute to the formation of GABA in the enteric nervous system. The oral administration of bacteria from this strain can influence GABAergic firing in the mice brain through the vagus nerve. Furthermore, stimulation of the vagal nerve through transcutaneous vagus nerve stimulation (tVNS) has been shown to affect processes thought to be GABAergic in humans. Finally, a similar behavioral effect has been found both for the administration of synthetic GABA and tVNS with regards to action cascading. Even if GABA is unable to cross the blood–brain barrier (BBB) at all in humans, an indirect effect through the enteric nervous system might be a viable route for an effect of GABA food supplements. The link between the oral administration of GABA, the vagal nerve and GABA levels in the brain has not been established yet, but in view of the available evidence it is a promising candidate for future research.

GABA dosage

It is not clear whether GABA taken as a supplement reaches the brain in large enough quantities to have an effect. There isn’t a set dosage for GABA at this time.

In a a double-blind, randomized study involving thirty undergraduate students of the Leiden University (29 females, 1 male, mean age = 19.5 years, range 18–22) participated in the GABA experiment, GABA was proven to have central nervous system action after an oral administration of 800 mg synthetic GABA by modulating fronto-striatal networks ¹³⁵⁾. Results showed that the administration of GABA, compared to placebo, increased action selection when an interruption (stop) and a change towards an alternative response were required simultaneously, and when such a change had to occur after the completion of the stop process. Therefore, the outcome is consistent with, and further supports, previous findings suggesting that response inhibition processes are modulated by the GABA-ergic system ¹³⁶⁾. An important limitation of that study is the small sample size, including predominantly female participants. Therefore, further studies are needed in order to verify the reliability and repeatability of their findings in larger samples that are balanced for gender.

GABA supplement side effects

There has not been enough research to uncover the side effects of GABA supplements. Furthermore, there isn’t enough information to be sure about the safety of GABA. For this reason, it’s best to play it safe and not use GABA if you are pregnant or breastfeeding.

What is holy basil

Holy basil also known as Tulsi or Ocimum sanctum L. (Ocimum tenuiflorum L.) is an aromatic shrub in the basil family Lamiaceae (tribe ocimeae) that is thought to have originated in north central India and now grows native throughout the eastern world tropics ¹⁾. Holy basil has been used as a medicinal plant for thousands of years in Indian traditional medicine Ayurveda and its allied herbalism disciplines for its diverse healing properties ²⁾. Holy basil plant is considered sacred and is worshipped in a sanctorum of its own in traditional Hindu temples, sacred groves, and households throughout the subcontinent and therefore its taxonomical synonym Ocimum sanctum L. is more popular in Indian scientific literature. Within Ayurveda, holy basil is known as “The Incomparable One,” “Mother Medicine of Nature” and “The Queen of Herbs,” and is revered as an “elixir of life” that is without equal for both its medicinal and spiritual properties ³⁾. Within India, holy basil has been adopted into spiritual rituals and lifestyle practices that provide a vast array of health benefits. This emerging science on holy basil, which reinforces ancient Ayurvedic wisdom, suggests that holy basil is a tonic for the body, mind and spirit that offers solutions to many modern day health problems ⁴⁾. A number of recent biochemical and physiological studies indicate that holy basil may possess antidiabetic ⁵⁾, antimicrobial ⁶⁾, anticancer ⁷⁾, adaptogenic ⁸⁾, and radioprotective ⁹⁾ properties. Daily consumption of holy basil is said to prevent disease, promote general health, wellbeing and longevity and assist in dealing with the stresses of daily life ¹⁰⁾. Holy basil is also credited with giving luster to the complexion, sweetness to the voice and fostering beauty, intelligence, stamina and a calm emotional disposition ¹¹⁾. In addition to these health-promoting properties, holy basil is recommended as a treatment for a range of conditions including anxiety, cough, asthma, diarrhea, fever, dysentery, arthritis, eye diseases, otalgia, indigestion, hiccups, vomiting, gastric, cardiac and genitourinary disorders, back pain, skin diseases, ringworm, insect, snake and scorpion bites and malaria ¹²⁾.

Holy basil is an erect, much branched subshrub, 30–60 cm tall with hairy stems and simple, opposite, green leaves that are strongly scented. Leaves have petioles and are ovate up-to 5 cm long, usually slightly toothed ¹³⁾. Recent molecular phylogenetic studies indicate that the tribe ocimeae is originated in tropical Asia and got introduced elsewhere ¹⁴⁾.

Figure 1. Holy basil (Ocimum sanctum L)

Holy basil phytochemical constituents

The chemical composition of holy basil is highly complex, containing many nutrients and other biologically active compounds, the proportions of which may vary considerably between strains and even among plants within the same field. Furthermore, the quantity of many of these constituents is significantly affected by differing growing, harvesting, processing and storage conditions that are not yet well understood ¹⁵⁾.

The nutritional and pharmacological properties of the whole herb in its natural form, as it has been traditionally used, result from synergistic interactions of many different active phytochemicals ¹⁶⁾. Consequently, the overall effects of holy basil cannot be fully duplicated with isolated compounds or extracts ¹⁷⁾. Because of its inherent botanical and biochemical complexity, holy basil standardization has, so far, eluded modern science. The holy basil leaf volatile oil ¹⁸⁾ contains eugenol (1-hydroxy-2-methoxy-4-allylbenzene [Figure 2]), euginal (also called eugenic acid), urosolic acid, carvacrol (5-isopropyl-2-methylphenol), linalool (3,7-dimethylocta-1,6-dien-3-ol), limatrol, caryophyllene (4,11,11-trimethyl-8-methylene-bicyclo[7.2.0]undec-4-ene), methyl carvicol (also called Estragol: 1-allyl-4-methoxybenzene) while the seed volatile oil have fatty acids and sitosterol; in addition, the seed mucilage contains some levels of sugars and the anthocyans are present in green leaves. The sugars are composed of xylose and polysaccharides ¹⁹⁾.

Although holy basil is known as a general vitalizer and increases physical endurance, it contains no caffeine or other stimulants ²⁰⁾. The stem and leaves of holy basil contain a variety of constituents that may have biological activity, including saponins, flavonoids, triterpenoids, and tannins ²¹⁾. In addition, the following phenolic actives have been identified, which also exhibit antioxidant and antiinflammatory activities, Rosmarinic acid ²²⁾. Two water-soluble flavonoids: Orientin (8-C-beta-glucopyranosyl-3’,4’,5,7-tetrahydroxyflav-2-en-3-one) and Vicenin (6-C-beta-D-xylopyranosyl-8-C-beta-D-glucopyranosyl apigenin), have shown to provide protection against radiation-induced chromosomal damage in human blood lymphocytes ²³⁾.

Figure 2. Holy basil eugenol (1-hydroxy-2-methoxy-4-allylbenzene)

Holy basil uses in Ayurveda and traditional medicine

Anti-anxiety and anti-depressant

The psychotherapeutic properties of holy basil have been explored in various animal experiments that reveal that holy basil has anti-anxiety and anti-depressant properties ²⁴⁾, with effects comparable to diazepam and antidepressants drugs ²⁵⁾. Animal studies further reveal that holy basil enhances memory and cognitive function ²⁶⁾ and protects against aging-induced memory deficits ²⁷⁾. Similarly, in human studies, holy basil has been observed to reduce stress, anxiety and depression ²⁸⁾, with a 6-week, randomized, double-blind, placebo-controlled study reporting that holy basil significantly improves general stress scores, sexual and sleep problems and symptoms such as forgetfulness and exhaustion ²⁹⁾.

While modern scientific studies suggest that holy basil is effective in treating a range of stressful conditions, within Ayurveda, holy basil is more commonly recommended as a preventive measure to enhance the ability to adapt to both psychological and physical stress and therefore prevent the development of stress-related diseases. To this end, many Ayurvedic practitioners recommend the regular consumption of holy basil tea as an essential lifestyle practice.

Liquid yoga

Regular consumption of holy basil tea may be compared with the regular practice of yoga, which can be considered “adaptogenic” through nurturing and nourishing the body — mind — spirit while fostering a sense of relaxation and wellbeing. In contrast, regular consumption of caffeinated beverages such a black and green tea (Camellia sinensis L.) and coffee (Coffea arabica L.) may be compared with more aerobic exercise, which confers health benefits through stimulation and activation.

Like yoga, holy basil has a calming effect that leads to clarity of thought, along with a more relaxed and calm disposition. The cognitive and memory-enhancing properties of holy basil therefore differ from those of caffeine-containing beverages such as coffee and tea, which heightens arousal and may cause physical and mental agitation. Furthermore, holy basil does not produce the same physical dependence as caffeine and can be safely consumed on a regular basis without the fear of withdrawal effects.

The drinking of tea and coffee has become an integral part of modern life and has been ritualized in many cultures to guide social interactions, set social agendas and invoke spiritual awareness. For example, sophisticated Asian tea ceremonies involve a whole set of rituals, tools and gestures that serve to transcend normal consciousness, while in the west the ritual of “afternoon tea” or “high tea” emphasizes the surroundings, equipment, manners and social circle. In less-formal situations, many people ritualize their morning cup of coffee and use the “meet-up for coffee” to arrange their social agendas, while the “tea break” is often built into the modern-day work routine. Yet, while tea and coffee have infiltrated their way into modern living, they have not yet attained the status that holy basil has within traditional Indian life.

Infection protection

holy basil has also been shown to be active against many animal pathogens, and this has led to holy basil being used in animal rearing to reduce infections in cows, poultry, goats, fish and silkworms. Holy basil’s activity against water-borne and food-borne pathogens further suggests that it can be used in the preservation of food stuffs ³⁰⁾ and herbal raw materials as well as for water purification ³¹⁾ and as a hand sanitizer ³²⁾.

Holy basil’s broad-spectrum activity, which includes activity against Streptococcus mutans, the organism responsible for tooth decay, further suggests that it can be used as a herbal mouth wash for treating bad breath, gum disease and mouth ulcers ³³⁾. This has been confirmed in clinical trials that have demonstrated that rinsing with holy basil is as effective as 0.2% Chlorhexidine and Listerine in reducing the levels of Streptococcus mutans ³⁴⁾ and that a herbal mouthwash that includes holy basil is preferred for its taste and convenience ³⁵⁾.

Holy basil’s unique combination of antibacterial antioxidant, anti-inflammatory and analgesic activities also makes it useful in wound healing ³⁶⁾. This is supported by experimental evidence that has shown that holy basil can increase wound-breaking strength and accelerate wound healing in laboratory animals. Holy basil has also been shown to have anti-ulcer and ulcer-healing activity that has been observed in many different animal models including aspirin-, indomethacin-, alcohol-, histamine-, reserpine-, serotonin-, acetic acid-, meloxicam-, cold restraint-, pyloric ligation- and stress-induced ulceration models ³⁷⁾. This anti-ulcer activity is attributed to multiple actions including the reduction of offensive factors such as acid-pepsin secretion and lipid peroxidation and the enhancement of gastric defensive factors such as mucin secretion, cellular mucus and longevity of mucosal cells ³⁸⁾.

Holy basil potential health benefits

Human clinical trials are lacking. In animal and in vitro experiments, effects of holy basil are largely attributed to antioxidant activity. Hypoglycemic activity and protective effects against noise stress have been studied, but clinical trials are lacking.

Holy basil dosage

Information is lacking. One clinical trial for hypoglycemic effect used 2.5 g leaves as dried powder in 200 mL water daily for 2 months.

Animal Studies (Pre-Clinical)

During the last two decades, holy basil has demonstrated various pre-clinical activities in animal models in vitro testing. Some such notable findings are reported here:

Antidiabetic

Ethanolic extract of holy basil significantly decreases the blood glucose, glycosylated hemoglobin and urea with a concomitant increase in glycogen, hemoglobin and protein in streptozotocin-induced diabetic rats ³⁹⁾. This extracts also resulted in an increase in insulin and peptide levels and glucose tolerance.

The constituents of holy basil leaf extracts have stimulatory effects on physiological pathways of insulin secretion, which may underlie its reported antidiabetic action ⁴⁰⁾.

Grover et al. ⁴¹⁾ suggested that treatment with holy basil extract for 30 days to normal rats fed with fructose for 30 days significantly lowered serum glucose level in comparison with control group. However, holy basil extract has no significant effect on hyperinsulinemia.

Ghosap et al. ⁴²⁾ unravel the possible mechanism of glucose-lowering activity of holy basil in male mice. The study suggested that holy basil decreases the serum concentration of both cortisol and glucose and also exhibited antiperoxidative effect. Therefore holy basil may potentially regulate corticosteroid- induced diabetic mellitus.

In another study the effect of holy basil on three important enzymes of carbohydrate metabolism [glucokinase (gk), hexokinase (hk) and phosphofructokinase (PFK) along with glycogen content of insulin-dependent (skeletal muscle and liver) and insulin-independent tissues (kidneys and brain) was studied by Vats et al ⁴³⁾ in streptozotocin (STZ, 65 mg/kg)-induced model of diabetes for 30 days in rats. Administration of holy basil extracts 200 mg/kg for 30 days lead to decrease in plasma glucose levels by approximately 9.06 and 24.4% on 15th and 30th day. holy basil significantly decreased renal but not liver weight (expressed as % of body weight) holy basil glycogen content in any tissue; also holy basil partially corrected the activity of glucokinase (gk), hexokinase (hk) and phosphofructokinase (PFK) distributed in the diabetic control.

holy basil (holy basil) leaf powder was fed at the 1% level in normal and diabetic rats for a period of one month and the result indicated a significant reduction in fasting blood sugar urogenic acid, total amino acids level. This observation indicates the hypoglycemic effect of holy basil in diabetic rats ⁴⁴⁾.

Chattopadyay also reported that oral administration of alcoholic extract of leaves of holy basil led to marked lowering of blood sugar level in normal, glucose-fed hyperglycemic and streptozotocin-induced diabetic rats ⁴⁵⁾. Furthermore, the extract potentiates the action of exogenous insulin in normal rats. The activity of the extract was 91.55 and 70.43% of that of Tolbutamide in normal and diabetic rats, respectively.

Cardiac activity

Oral feeding of hydroalcoholic extract of holy basil (100 mg/kg) to male Wister rats subjected to chronic-resistant stress (6 h/day for 21 days) significantly prevented the chronic-resistant stress/induced rise in plasma cAMP level, myocardial superoxide dismutase and catalase activities as well as the light microscopic changes in the myocardium ⁴⁶⁾.

Wister rats fed with fresh leaf homogenate of holy basil (50 and 100 mg/kg body weight) daily 30 days inhibit isoproterenol-induced changes in myocardial superoxide dismutase, glutathione peroxidase and reduced glutathione ⁴⁷⁾.

In another study effect of pre- and co-treatment of hydroalcoholic extract of holy basil at different doses (25, 50, 75, 100, 200 and 400 mg/kg) was investigated against isoproterenol (ISO, 20 mg/kg, Sc) myocardial infarction in rats. holy basil at the dose of 25, 50, 75 and 100 mg/kg significantly reduced glutathione (GSH), superoxide dismutase and LDH levels. In this study ⁴⁸⁾, it was observed that holy basil at the dose of 50 mg/kg was found to demonstrate maximum cardioprotective effect.

The generation of drug-induced oxygen radicals in heart cells led to cardiac lipid membrane peroxidation ⁴⁹⁾. Urosolic acid(UA) isolated from holy basil have been identified as a protector against Adriamycin (ADR)-induced lipid peroxidation. Protection with UA was 13 and 17% in liver and heart microsomes, respectively. On combination with oleanolic acid (OA) isolated from Eugenia jumbolata , it increased to 69%.

Wound healing activity

Shetty et al. ⁵⁰⁾ evaluated the wound healing effect of aqueous extract of holy basil in rats. Wound-breaking strength in incision wound model, epithelization period and percent wound concentration in excision wound model were studied owing to increased per cent wound contraction. Holy basil may be useful in the management of abnormal healing such as keloids and hypertropic scars.

Ethanolic extract of leaves of holy basil was investigated for normal wound healing and dexamethasone-depressed healing ⁵¹⁾.The extract significantly increased the wound breaking strength, wound epithelializes fast and wound contraction was significantly increased along with increase in wet and dry granulation tissue weight and granulation tissue breaking strength. The extract also significantly decreases the anti-healing activities of dexamethasone in all wound healing models.

Radio-protective effect

Radio-protective effect of aqueous extract of holy basil (40 mg/kg, for 15 days) in mice exposed to high doses (3.7 MBq) of oral 131 iodine was investigated by studying the organ weights, lipid peroxidation and antioxidant defense enzyme in various target organs like liver, kidney, salivary glands and stomach at 24 h after exposure ⁵²⁾. Pretreatment with holy basil in radioiodine-exposed group showed significant reduction in lipid peroxidation in both kidney and salivary glands. In liver, reduced glutathione (GSH) levels showed significant reduction after radiation exposure while pretreatment with holy basil exhibited less depletion in GSH level even after 131 iodine exposure. However, no such changes were observed in the stomach. The results indicate the possibility of using aqueous extract of holy basil for ameliorating 131 iodine induced damage to the salivary glands.

Two polysaccharides isolated from holy basil could prevent oxidative damage to liposomal lipids and plasmid DNA induced by various oxidants such as iron, AAPH and gamma radiation ⁵³⁾.

Vrinda et al. ⁵⁴⁾ reported that two water-soluble flavonoids, Orientin (Ot) and Vicenin (Vc), isolated from the leaves of holy basil provide significant protection against radiation, lethality and chromosomal aberration in vivo. In order to select the most effective drug concentration, fresh whole blood was exposed to 4 Gy of cobalt-60 gamma radiation with holy basil without a 30 min pretreatment with 6.25, 12.5, 15, 17.5 and 20 micron of Ot/Vc in micronucleus test. Radiation significantly increased the micronucleus (MN) frequently. Pretreatment with either Ot or Vc at all concentration-dependent manner, with optimum effect at 17.5 μm.

The effect of aqueous extract of leaves of holy basil against radiation lethality[30] and chromosome damage was studied by radiation-induced lipid peroxidation in liver. Adult Swiss mice were injected with 10 mg/kg of gamma radiation 30 min after last injection. Glutathione (GSH) and the antioxidant enzymes glutathione transferase (GST), reductase (GSRx), peroxidase (GSPx) and superoxide dismutase (SOD) as well as lipid peroxide (LPx) activity were estimated in the liver at 15 min, 30 min, 1, 2, 4 and 8 h post-treatment. Aqueous extract itself increased the GSH and enzymes significantly above normal level, whereas radiation significantly reduced all the values and significantly increased the lipid peroxidation rate, reaching a maximum value at 2 h after exposure (3.5 times of control). Aqueous extract significantly reduced the lipid peroxidation and accelerated recovery to normal levels.

In a comparative study of radioprotection by ocimum flavonoids and synthetic aminothiol protectors in mouse showed Ocimum flavonoids as promising human radiation protectant ⁵⁵⁾. In this study, adult Swiss mice were injected intraperitoneally with 50 μg/kg body weight of Orientin (OT) or vicenin (Vc) 20 mg/kg body weight of 2-ercaptopropionyl glycine (MPG) 150 mg/kg body weight of WR2721 and exposed to whole body irradiation of 2 Gy gamma radiation 30 min later. After 24 hours, chromosomal aberrations were studied in the bone marrow of the femur by routine metaphase preparation after colchicines treatment. Pretreatment with all the protective compounds resulted in a significant reduction in the percentage of aberrant metaphases. Vicenin produced the maximum reduction in per cent aberrant cells while MPG was the least effective; OT and WR-2721 showed an almost similar effect.

Ganasoundari et al. ⁵⁶⁾ investigated the radio-protective effect of the leaf extract of holy basil (OE) in combination with WR-2721 (WR) on mouse bone marrow. Adult Swiss mice were injected intraperitoneally with OE (10 mg/kg for five consecutive days) alone or 100-400 mg/kg WR (Single dose) holy basil combination of the two and whole body was exposed to 4.5Gy gamma irradiation (RT). Metaphase plates were prepared from femur bone marrow on days 1, 2, 7 and 14 post-treatment and chromosomal aberrations were scored. Pretreatment with leaf extract of holy basil or WR individually resulted in a significant decrease in aberrant cells as well as different types of aberrations. The combination of the two further enhanced this effect; resulting in a two-fold increase in the protection factors (PF = 6.68) compared to 400 mg/kg WR alone.

Genotoxicity

In vivo cytogenetic assay in Allium cepa root tip cells has been carried out to detect the modifying effect of holy basil aqueous leaf extract against chromium (Cr) and mercury (Hg)-induced genotoxicity ⁵⁷⁾. It was observed that the roots post-treated with the leaf extract showed highly significant recovery in mitotic index and chromosomal aberrations. When compared to pre-treated (Cr/Hg) samples, the lower doses of the leaf extract were found to be more effective than the higher doses.

Immu-21, a poly-herbal formulation containing holy basil and other herbal extracts when given at 100 mg per kg daily over 7 days and 300 mg/kg daily over 14 days inhibited both cyclophosphamide (40 mg/kg intraperitoneal)-induced classical and non-classical chromosomal aberration (40–60% of control) ⁵⁸⁾. This also reduces the increase in micronuclei in the bone marrow erythrocytes of mice treated with cyclophosphamide.

Antioxidant

The antioxidant capacity of essential oils obtained by steam hydrodistillation from holy basil was evaluated using a high-performance liquid chromatography (HPLC) based hypoxanthine xanthine oxidase and OPPH assays ⁵⁹⁾. In hypoxanthine xanthine oxidase assay, strong antioxidant capacity was evident from holy basil (IC50 = 0.46 μL/ml).

In another study the aqueous extract of holy basil significantly increases the activity of anti-oxidant enzymes such as superoxide dismutase, catalase level in extract-treated group compared to control ⁶⁰⁾.

Aqueous extract of holy basil inhibit the hypercholesterolemia-induced erythrocyte lipid peroxidation activity in a dose-dependent manner in male albino rabbits ⁶¹⁾. Oral feeding also provides significant leaver and aortic tissue protection from hypercholestrolemia-induced peroxidative damage.

The effect of methanolic extract of holy basil leaves in cerebral reperfusion injury as well as long-term hypoperfusion was studied by Yanpallewar et al. ⁶²⁾. Holy basil pretreatment (200 mg/kg/day for 7 days) prevented reperfusion-induced rise in lipid peroxidation and superoxide dismutase. Holy basil pretreatment also stabilized the levels of tissue total sulfhydryl group during reperfusion.

Hypolipidemic

Administration of holy basil seed oil (0.8 gm/kg body weight/day) for four weeks, in cholesterol-fed (100 mg/kg body weight/day) rabbits significantly decreases serum cholesterol, triacylglycerol and LDL + VLDL cholesterol as compared to untreated cholesterol-fed group suggesting the hypo-cholesterolemic activity of holy basil ⁶³⁾.

Fresh leaves of holy basil mixed 1 and 2 g in 100 gm of diet given for four weeks brought about significant changes in the lipid of normal albino rabbits ⁶⁴⁾. This resulted in significant lowering in serum total cholesterol, triglyceride, phospholipids and LDL-cholesterol level and significant increase in the HDL-cholesterol and total fecal sterol contents.

Antimicrobial

Singh et al. ⁶⁵⁾ in his study suggested that higher content of linoleic acid in holy basil fixed oil could contribute towards its antibacterial activity. The holy basil oil show good antibacterial activity against Staphylococcus aureus, Bacillus pumius and Pseudomonas aeruginosa, where S. aureus was the most sensitive organism.

Geeta et al. ⁶⁶⁾ studied that the aqueous extract of holy basil (60 mg/kg) show wide zones of inhibition compared to alcoholic extract against Klebsiella, E. coli, Proteus, S. aureus and Candida albicans when studied by agar diffusion method. Alcoholic extract showed wider zone for Vibrio cholerae.

Effect on gene transcription

The genes that have direct role in artherogenesis include LDRL, LxRalpha, PPARs, CD-36 because these genes control lipid metabolism, cytotoxin production and cellular activity within the arterial wall. To know whether or not the polyphenols extracted from holy basil have any effect on the transcription of these genes, Kaul et al. ⁶⁷⁾ cultured human mononuclear cells in the presence of polyphenols extracted from holy basil Transcriptional expression of these genes was measured by using RT-PCR and SCION IMAGE analysis software. These polyphenolic extracts were found to have the inherent capacity to inhibit the transcriptional expression of these genes.

Gastroprotective

The standardized methanolic extract of leaves of holy basil given in doses of 50–200 mg/kg orally twice daily for five days showed dose-dependent ulcer protective effect against cold-restraint stress-induced gastric ulcers. Optimal effective dose (100 mg/kg) of holy basil extract showed significant ulcer protection against ethanol and pyloric ligation induced gastric ulcer but was ineffective against aspirin-induced ulcer ⁶⁸⁾. Holy basil extract (100 mg/kg) also inhibits the offensive acid pepsin secretion and lipid peroxidation and increases the gastric defensive factors like mucin secretion, cellular mucus and lifespan of mucosal cells.

Dharmani et al. ⁶⁹⁾ evaluated the anti-ulcerogenic activity in cold-restraint, aspirin, alcohol, pyloric ligation induced gastric ulcer models in rats, histamine-induced duodenal ulcer in guinea pigs and ulcer healing activity in acetic acid induced (AC) chronic ulcer model. Osimum sanctum L. at a dose of 100 mg/kg was found to be effective in cold-restraint (65.07%), aspirin (63.49%), alcohol (53.87%), pyloric ligation (62.06%) and histamine (61.76%) induced ulcer models and significantly reduced free, total acidity and peptic activity by 72.58, 58.63 and 57.6%, respectively, and increased mucin secretion by 34.61% conclusively holy basil could act as a potent therapeutic agent against peptic ulcer disease.

The antiulcerogenic property of holy basil was studied in pyloric-ligated and aspirin-treated rats ⁷⁰⁾. The holy basil extract of reduced ulcer index, free and total acidity on acute and chronic administration seven days pretreatment increased the mucus secretion also. So it may be concluded that holy basil extract has anti-ulcerogenic property against experimental ulcers and it is due to its ability to reduce acid secretion and increase mucus secretion.

Immunomodulatory effect

Immunotherapeutic potential of aqueous extract of holy basil leaf in bovine sub-clinical mastitis was investigated after intramammary infusion of aqueous extract ⁷¹⁾. The results revealed that the aqueous extract of holy basil treatment reduced the total bacterial count and increased neutrophil and lymphocyte counts with enhanced phagocytic activity and phagocytic index.

In another study, the immunomodulatory effect of holy basil seed oil was evaluated in both non-stressed and stressed animals ⁷²⁾. Holy basil seed oil (3 ml/kg, intraperitoneal) produced a significant increase in anti-sheep red blood cells antibody titer and a decrease in percentage histamine release from peritoneal mast cell of sensitized rats (humoral immune responses) and decrease in food pad thickness and percentage leucocyte migration inhibition (cell-mediated immune responses). Co-administration of diazepam (1 mg/kg, subcutaneously), a benzodiazepine with holy basil seed oil (1 mg/kg, intraperitoneal) enhanced the effect of holy basil seed oil on resistant stress induced changes in both humoral and cell-mediated immune responses. Further, flumazenil (5 mg/kg, intraperitoneal) a central benzodiazepine receptor antagonist inhibited the immunomodulatory action of holy basil seed oil on resistant stress induced immune responsiveness. Thus, holy basil seed oil apparatus to modulate both humoral and cell-mediated immune responsiveness and these immunomodulatory effects may be mediated by GABAnergic pathway.

Godhwani et al. ⁷³⁾ investigated the immunoregulatory profile of methanolic extract and an aqueous suspension of holy basil leaves to antigenic challenge of Salmonella typhosa and sheep erythrocytes by quantifying agglutinating antibodies employing the Widal agglutination and sheep erythrocyte agglutination tests and E-rosette formation in albino rats. The data of the study indicate an immunostimulation of humoral immunogenic response as represented by an increase in antibody titer in both the Widal and sheep erythrocyte agglutination tests as well as by cellular immunologic response represented by E-rosette formation and lymphocytosis.

Sexually transmitted disease

Extract of holy basil caused inhibition of Neisseria gonorrhoeae clinical isolates and WHO organization strains ⁷⁴⁾. The activity is comparable to penicillin and ciprofloxacin.

Effect on central nervous system

Different extracts of stem, leaf and stem callus (induced on slightly modified Murashige and Skoog’s medium and supplemented with 2,4-dichlorophenonyacetic acid and kinetin) were tested for anticonvulsant activity by maximal electroshock model using Phenytoin as standard ⁷⁵⁾. It was observed that ethanol and chloroform extractives of stem, leaf and stem calli were effective in preventing tonic convulsions induced by transcorneal electroshock.

Ethanolic extract of leaves of holy basil prolonged the time of lost reflex in mice due to pentobarbital, decreased the recovery time and severity of electroshock and pentylenetetrazole-induced convulsions and decreased apomorphine-induced fighting time and ambulation in ‘open field’ studies ⁷⁶⁾. In the forced swimming behavioral despair model, the extract lowered immobility in a manner comparable to Imipramine. This action was blocked by haloperidol and sulpiride, indicating a possible action involving dopaminergic neurons. In similar studies, there was a synergistic action when the extract was combined with bromocriptine, a potent Dopamine 2-receptor agonist.

Nootropic agents are a new class of drugs used in situations where there is organic disorder in learning abilities. Joshi and Parle ⁷⁷⁾ assessed the potential of holy basil extract as a nootropic and anti-amensic agent in mice. Aqueous extract of derived whole plant of holy basil ameliorated the amensic effect of scopolamine (0.04 mg/kg), diazepam (1 mg/kg) and aging-induced memory deficits in mice. Elevated plus maze and passive avoidance paradigm served as the exteroceptive behavioral models. holy basil extract decreased transfer latency and increased step-down latency, when compared to control (piracetam-treated), scopolamine and aged groups of mice significantly. So holy basil preparation could be beneficial in the treatment of cognitive disorders such as dementia and Alzheimer’s disease.

Methanolic extract of holy basil root extract at a dose of 400 mg/kg intraperitoneal increases the swimming time of mouse in a despair swim test model, suggesting a central nervous system stimulant and/or anti-stress activity of holy basil ⁷⁸⁾.

Analgesic effect

The analgesic activity of alcoholic leaf extract of holy basil (50, 100 mg/kg, ip; 50, 100, 200 mg/kg, oral) was tested in mice using glacial acetic acid induced writhing test ⁷⁹⁾. Holy basil reduced the number of writhes. Holy basil (50, 100 mg/kg intraperitoneal) also increased the tail withdrawal latency in mice.

Anti-fertility

Benzene extract of holy basil leaves have a reversible anti-fertility effect, as holy basil extract (250 mg/kg body weight) for 48 days decreases the total sperm count, sperm motility and forward velocity ⁸⁰⁾. The percentage of abnormal sperm increased in caudal epididymal fluid and the fructose content decreased in the caudal plasma of the epididymis and the seminal vesicles. All these parameters returned to normal two week after the withdrawal of the treatment.

Anthelmintic activity

The anthelmintic activity of the essential oil from holy basil was evaluated by Caenorhabditis elegance model ⁸¹⁾. Eugenol exhibited an ED50 of 62.1 μg/ml and being the predominant component of the essential oil, it was suggested as the putative anthelmintic principle.

Antiinflammatory

Compounds isolated from holy basil extract, Civsilineol, Civsimavatine , Isothymonin, Apigenin, Rosavinic acid and Eugenol were observed for their anti-inflammatory activity or cyclooxygenase inhibitory activity ⁸²⁾. Eugenol demonstrated 97% cyclooxygenase-1 inhibitory activity when assayed at 1000 μM concentration (pn). Civsilineol, Civsimavitin, Isothymonin, Apigenin and Rosavinic acid displayed 37, 50, 37, 65 and 58% cyclooxygenase-1 inhibitory activity, respectively, when assayed at 1000 μM concentrations. The activities of these compounds were comparable to Ibuprofen, Naproxen and aspirin at 10, 10 and 1000 μM concentrations.

Singh in his study ⁸³⁾ reported that linoleic acid present in different amount in the fixed oil of different species of holy basil has the capacity to block both the cyclooxygenase and lipoxygenase pathways of arachidonate metabolism and could be responsible for the anti-inflammatory activity.

A methanolic extract and an aqueous suspension of holy basil (500 mg/kg) inhibited acute as well as chronic inflammation in rats as tested by carrageenin-induced pedal edema and cratonoil -induced granuloma and exudates, respectively, and the response was comparable to the response observed with 300 mg/kg of sodium salicylate ⁸⁴⁾. Both the extract and suspension showed analgesic activity in mouse hot plate procedure, and the methanol extract caused an increase in tail withdrawal reaction time of a sub-analgesic dose of morphine. Both preparations reduced typhoid–paratyphoid A–B vaccine-induced pyrexia. The antipyretic action of methanol extract and aqueous suspension was weak and of shorter duration than that of 300 mg/kg sodium salicylate.

Anticancer

Fresh holy basil leaf paste (topically) aqueous and ethanolic extract (orally) for their chemopreventive activity against 7,12-dimethylbenzaanthracene (DMBA) induced (0.5%) hamster buccal pouch carcinogenesis ⁸⁵⁾. Incidence of papillomas and squamous cell carcinomas were significantly reduced and increased the survival rate in the topically applied leaf paste and orally administered extracts to animals. Histopathological observation made on the mucosa confirmed the profound effect of the orally administered aqueous extract than other.

Prasbar et al. ⁸⁶⁾ in their study reported that holy basil leaf extract blocks or suppresses the events associated with chemical carcinogenesis by inhibiting metabolic activation of the carcinogen. In this study, primary cultures of rat hepatocytes were treated with 0–500 μg of holy basil extract for 24 h and then with 7,12-dimethaylbenz[a] anthracene (DMBA, 10 or 50 μg) for 18 h. Cells were then harvested and their DNA was isolated and analyzed by 32p post-labeling. A significant reduction in the levels of DMBA/DNA adducts was observed in all cultures pretreated with holy basil extract. Hepatocytes that were treated with the highest dose of extract (500 μg) showed a maximum reduction of 93% in the mean values of DMBA/DNA adducts. This suggests the inhibition of metabolic activation of carcinogen.

The chemopreventive activity of holy basil seed oil of holy basil was evaluated against subsequently injected 20-methyl cholanthrene-induced fibrosarcoma tumors in the thigh region of Swiss albino mice ⁸⁷⁾. Supplementation of maximal-tolerated dose (100 μl/kg body wt.) of the oil significantly reduced 20-methaylcholathrene-induced tumor incidence and tumor volume. The enhanced survival rate and delay in tumor incidence was observed in seed oil supplemented mice. Liver enzymatic, non-enzymatic antioxidants and lipid peroxidation end product, malondialdehyde level were significantly modulated with oil treatment as compared to untreated 20-methylcholathrene injected mice. The chemopreventive efficacy of 100 μl/kg holy basil seed oil was comparable to that of 80 mg/kg vitamin E.

Thyroid activity

The extract of holy basil leaf extract on the changes in the concentrations of serum Triiodothyronine (T3), Thyronine (T4) and serum cholesterol were investigated ⁸⁸⁾. Holy basil leaf extract at the dose of 0.5 g/kg body weight for 15 days significantly decreased serum T4 concentration; however, no marked changes were observed in serum T3 level, T3/T4 ratio and in the concentration of serum cholesterol. It appears that holy basil leaf extract is antithyroidic in nature.

Miscellaneous activity

Graded dose of 100, 150, 200 and 400 mg/kg of holy basil leaves extract significantly decreases the sexual behavioral score in adult male Wistar rats ⁸⁹⁾. Broadband white noise exposure (100 dB) in Wistar strain male albino rats significantly increased the level of dopamine (DA), serotonin (5-HT) and 5-HT turnover in many of the discrete brain regions during sub-chronic noise exposure (4 h daily, 15 days). In acute (4 h for 1 day) and chronic noise exposures (4 h daily for 30 days) the levels were significantly altered in certain region ⁹⁰⁾. The intraperitoneal administration of 70% ethanolic extract of holy basil at dosage of 100 mg/kg body weight to animals subjected to noise exposure has prevented the noise-induced increase in neurotransmitter levels without affecting the normal levels. This suggests that holy basil can be a probable herbal remedy for noise-induced biogenic amine alterations. Gupta ⁹¹⁾ studied the anticataract effect of holy basil extract on selenite-induced cataract (25 micromole/kg body weight) in 9 day old rat pups. Holy basil (5 and 10 mg/kg body wt.) injected intraperitoneally 4 h prior to selenite challenge reduces the incidence of selenite cataract by 20 and 60%, respectively, and prevented protein insolubilization as well.

Halder et al. ⁹²⁾ found aqueous extract of holy basil as the most effective aldose reductase inhibitor with a significant inhibition of 38.05% considering the aldose reductase activity of normal rat lenses as 100%. The IC50 value was found to be 20 μg/ml.

Holy basil extract (10 mg/kg body wt., oral) before and after mercury (HgCl2) intoxication (5 mg/kg body wt.) showed a significant decrease in lipid peroxidation ⁹³⁾. Serum glutamate pyruvate transaminase (SGPT) activities compared to HgCl2-induced values suggests that holy basil extract provides protection against HgCl2-induced toxicity in mice.

Holy basil fixed oil increases blood clotting time and percentage increase was comparable to aspirin and could be due to inhibition of platelet aggregation ⁹⁴⁾. Holy basil oil also increased pentobarbitone-induced sleeping time in rats indicating probable inhibitory effect of holy basil oil towards cytochromic enzyme responsible for hepatic metabolism of pentobarbitone.

Noise stress causes leucopenia, increased corticosterone level and enhances the neutrophil functions as indicated by increase in the candida phagocytosis and nitro blue tetrazolium reduction ⁹⁵⁾. Pre-treatment with the holy basil extract brought back the stress altered values to normal levels indicating the stress alleviating effect of holy basil.

Holy basil side effects

Information is limited. Few adverse reactions were noted in a Cochrane review of holy basil studies ⁹⁶⁾. Reversible inhibition of spermatogenesis, and decreased total sperm count and motility have been demonstrated in mice. Two animal studies suggested that large amounts of holy basil might negatively affect fertility ⁹⁷⁾, ⁹⁸⁾. Safety during pregnancy and lactation has not been investigated; until more is known, holy basil should probably be avoided at those times ⁹⁹⁾.