ginger root
ginger health benefits

What is Ginger

Ginger (Zingiber officinale) is a tropical plant that has green-purple flowers and a fragrant underground stem (called a rhizome). The rhizome (underground part of the stem) is the part commonly used as a spice. It is often called ginger root, or simply ginger. Ginger belongs to the Zingiberaceae family and the Zingiberaceae family consists of 49 genera and 1,300 species, of which there are 80–90 species of Zingiber and 250 species of Alpinia 1). It is widely used as a flavoring or fragrance in foods, beverages, soaps, and cosmetics 2). Ginger is a very popular spice and the world production is estimated at 100,000 tons annually, of which 80% is grown in China 3). Ancient Sanskrit, Chinese, Greek, Roman, and Arabic texts discussed the use of ginger for health-related purposes. In Asian medicine, dried ginger has been used for thousands of years to treat stomach ache, diarrhea, and nausea 4). Over the last few years, interest in ginger or its various components as valid preventive or therapeutic agents has increased markedly, and scientific studies focusing on verification of ginger’s pharmacological and physiological actions have likewise increased 5). Today, ginger is used as a dietary supplement for postsurgery nausea; nausea caused by motion, chemotherapy, or pregnancy; rheumatoid arthritis; and osteoarthritis.

Usage, preparation and processing of Ginger

Ginger is used in numerous forms, including fresh, dried, pickled, preserved, crystallized, candied, and powdered or ground. Common forms of ginger include the fresh or dried root, tablets, capsules, liquid extracts, and teas.

The flavor is somewhat peppery and slightly sweet, with a strong and spicy aroma. The concentration of essential oils increases as ginger ages and, therefore, the intended use of the rhizome determines the time when it is harvested. If extracting the oil is the main purpose, then ginger can be harvested at 9 months or longer. Ginger is commonly pickled in sweet vinegar, which turns it a pink color; this form is popular with sushi. Ginger harvested at 8-9 months has a tough skin that must be removed before eating, and the root is more pungent and is used dried or pulverized into ground ginger. This is the form most commonly found in our spice racks and used in cookies, cakes, and curry mixes. Candied or crystallized ginger is cooked in sugar syrup and coated with granulated sugar. Ginger harvested at 5 months is not yet mature and has a very thin skin, and the rhizomes are tender with a mild flavor and are best used in fresh or preserved forms.

Table 1. Ginger Root (Raw) Nutrition Content

[Source: United States Department of Agriculture, Agriculture Research Service. USDA Food Composition Databases. 6)]

Bioactive Components of Ginger

Pharmacologically, ginger, similar to other plants, is a very complex mixture of compounds. At least 115 constituents in fresh and dried ginger varieties have been identified by a variety of analytical processes, among them gingerols, beta-carotene, capsaicin, caffeic acid, volatile oils and curcumin 7). The unique fragrance and flavor of ginger come from its natural oils, the most important of which is gingerol. 6-Gingerol is the major pharmacologically-active component of ginger. It is known to exhibit a variety of biological activities including anticancer, anti-inflammation, and anti-oxidation 8). 6-Gingerol has been found to possess anticancer activities via its effect on a variety of biological pathways involved in apoptosis, cell cycle regulation, cytotoxic activity, and inhibition of angiogenesis 9). Thus, due to its efficacy and regulation of multiple targets, as well as its safety for human use, 6-gingerol has received considerable interest as a potential therapeutic agent for the prevention and/or treatment of various diseases.

Gingerols are the major constituents of fresh ginger and are found slightly reduced in dry ginger, whereas the concentrations of shogaols, which are the major gingerol dehydration products, are more abundant 10) in dry ginger than in fresh ginger. At least 31 gingerol-related compounds have been identified from the methanolic crude extracts of fresh ginger rhizome 11). Ginger has been fractionated into at least 14 bioactive compounds, including [4]-gingerol, [6]-gingerol, [8]-gingerol, [10]-gingerol, [6]-paradol, [14]-shogaol, [6]-shogaol, 1-dehydro-[10]-gingerdione, [10]-gingerdione, hexahydrocurcumin, tetrahydrocurcumin, gingerenone A, 1,7-bis-(4′ hydroxyl-3′ methoxyphenyl)-5-methoxyhepthan-3-one, and methoxy-[10]-gingerol 12). The proportion of each individual component in a sample of ginger depends on country of origin, commercial processor, and whether the ginger is fresh, dried, or processed 13). Of the bioactive pungent components of Jamaican ginger, including [6]-, [8]-, and [10]-gingerols and [6]-shogaol, [6]-gingerol appears to be the most abundant pungent bioactive compound in most of the oleoresin samples studied 14). Although phylogenetic analysis has showed that all ginger samples from widely different geographical origins are genetically indistinguishable, metabolic profiling showed some quantitative differences in the contents of [6]-, [8]-, and [10]-gingerols 15). An examination of the concentrations of [6]-, [8]-, and [10]-gingerols and [6]-shogaol in 10 different ginger-root dietary supplements purchased randomly from a variety of pharmacies and health food stores yielded some disconcerting results 16). Perhaps not surprisingly, the content of these active components was found to vary extensively from none or very minute amounts to several milligrams per gram. In addition, the suggested serving size ranged from about 250 mg to 4.8 g/day 17). The basis for the wide range of dosing is not clear. These studies suggest that ginger contains a variety of bioactive compounds and standardization of contents is critically lacking.

General Antioxidant Properties of Ginger

The presence of oxidative stress is associated with numerous diseases and a common mechanism often put forth to explain the actions and health benefits of ginger is associated with its antioxidant properties 18), 19). Ginger was reported to decrease age-related oxidative stress markers 20) and was suggested to guard against ethanol-induced hepatotoxicity by suppressing oxidative consequences in rats treated with ethanol 21). Ginger root contains a very high level (3.85 mmol/100 g) of total antioxidants, surpassed only by pomegranate and some types of berries 22). The phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA), promotes oxidative stress by activating the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system or the xanthine oxidase system or both. Ginger was reported to suppress TPA-induced oxidative stress in human promyelocytic leukemia (HL)-60 cells and Chinese hamster ovary AS52 cells 23). Others have shown that ginger compounds effectively inhibit superoxide production 24). Several animal studies indicate that ginger suppresses lipid peroxidation and protects the levels of reduced glutathione 25), 26), 27), 28), 29), 30).

Reactive nitrogen species, such as nitric oxide (NO), influence signal transduction and cause DNA damage, which contributes to disease processes. Nitric oxide is produced by inducible nitric oxide synthase (iNOS), which is stimulated in response to various stresses. [6]-gingerol was reported to dose-dependently inhibit NO production and reduce iNOS in lipopolysaccharide (LPS)-stimulated mouse macrophages 31). [6]-gingerol also effectively suppressed peroxynitritemediated oxidative damage. Ippoushi et al. 32) later proposed that [6]-gingerol and peroxynitrite form a symmetric dimer with [6]-gingerol covalently linked at the aromatic ring of peroxynitrite, attenuating peroxynitrite-induced oxidation and nitration reactions 33). [6]-shogaol, 1-dehydro-[10]-gingerdione, and [10]-gingerdione also decreased LPS-induced NO production, and [6]-shogaol and 1-dehydro-[10]-gingerdione were reported to effectively reduce iNOS expression 34). In the bromobenzene (BB)-induced hepatotoxicity model, orally given ginger extract (100 mg/kg body weight) normalized NO levels and total and reduced glutathione levels, and also decreased the level of lipid peroxidation 35). Ginger consumption has also been reported to decrease lipid peroxidation and normalize the activities of superoxide dismutase and catalase, as well as GSH and glutathione peroxidase, glutathione reductase, and glutathione-S-transferase, in rats 36). Ginger supplementation before ischemia/reperfusion resulted in a higher total antioxidant capacity (i.e., normalized glutathione peroxidase and superoxide dismutase activities) and lower total oxidant (lower tissue malondialdehyde, NO, and protein carbonyl contents) status levels compared to an untreated group of Wistar albino rats 37). Overall, the rats fed ginger (5%) experienced less kidney damage due to oxidative stress induced by ischemia/reperfusion (Uz E, Karatas O. F, Mete E, Bayrak R, Bayrak O, Atmaca A. F, Atis O, Yildirim M. E, Akcay A. The effect of dietary ginger (Zingiber officinals Rosc.) on renal ischemia/reperfusion injury in rat kidneys. Ren Fail. 2009;31(4):251–60. https://www.ncbi.nlm.nih.gov/pubmed/19462272)).

Ginger extract has been reported to exert radioprotective effects in mice exposed to gamma radiation 38), and the effect was associated with decreased lipid peroxidation and protection of GSH levels 39). [6]-gingerol pretreatment also decreased oxidative stress induced by ultraviolet B (UVB) and activated caspase-3, -8, -9, and Fas expression 40). Evidence does seem to suggest that ginger and some of its components are effective antioxidants in vitro. However, whether the physiological activity occurs in humans in vivo is not clear, and the specific mechanism and cellular targets are still to be determined.

Anti-Inflammatory Effects of Ginger

One of the many health claims attributed to ginger is its purported ability to decrease inflammation, swelling, and pain. [6]-gingerol 41), a dried ginger extract, and a dried gingerol-enriched extract 42) were each reported to exhibit analgesic and potent anti-inflammatory effects. Ginger has been suggested to be effective against inflammation, osteoarthritis, and rheumatism 43). However, inconsistencies in clinical studies have led to debate regarding the effectiveness and safety of ginger for treatment of arthritis 44).

Earlier animal studies suggest that rat hind limbs perfused with [6]-gingerol showed increased heat production that was associated with increased oxygen consumption and lactate efflux 45). The thermogenesis was at least partly associated with vasoconstriction independent of adrenergic receptors or secondary catecholamine release. In contrast, larger doses of ginger components inhibited oxygen consumption, which was attributed to disruption of mitochondrial function 46). These results were supported in a later study in which rats that were given a single intraperitoneal injection of [6]-gingerol (2.5 or 25 mg/kg) exhibited a rapid, marked drop in body temperature and a significant decrease in metabolic rate 47).

In addition, salicylate has been found in ginger in amounts of 4.5 mg/100 gm fresh root 48). This would correspond to <1 mg salicylate in 1 capsule of the ginger extract. The actions and especially the interactions of these ingredients have not been (and probably can not be easily) evaluated. Various powders, formulations, and extracts have, however, been commercially used and tested, both in vitro and in vivo, in animal models. In these models, ginger has been shown to act as a dual inhibitor of both cyclooxygenase (COX) and lipooxygenase 49), to inhibit leukotriene synthesis 50) and to reduce caregeenan-induced rat-paw edema and yeast-induced fever 51), 52), an animal model of inflammation.

 

Researchers have hypothesized that the anti-inflammatory effects of ginger might be related to its ability to inhibit prostaglandin and leukotriene biosynthesis 53). Some others have showed that gingerols actively inhibit arachidonate 5-lipoxygenase, an enzyme of leukotriene biosynthesis 54). [8]-gingerol, but not [6]-gingerol, was shown to inhibit cyclooxygenase-2 (COX-2) expression, which is induced during inflammation to increase formation of prostaglandins 55). Others have also reported that ginger extract suppresses the activation of tumor necrosis factor α (TNF-α) and expression of COX-2 in human synoviocytes 56). Proinflammatory cytokines such as TNF-α, interleukin (IL)-1β, and IL-12, which are produced primarily by macrophages, play an important role in sepsis, ischemia/reperfusion injury, and transplant rejection. [6]-gingerol was reported to inhibit the production of proinflammatory cytokines from LPS-stimulated peritoneal macrophages, but to have no effect on the function of antigen presenting cells (APC) or the LPS-induced expression of proinflammatory chemokines. However, this same group later reported that a ginger extract attenuated the production of IL-12, TNF-α, and IL-1β proinflammatory cytokines and RANTES (regulated upon activation, normal T cell expressed and secreted) and monocyte chemoattractant protein 1 (MCP-1) proinflammatory chemokines in LPS-stimulated murine peritoneal macrophages 57). In general, ginger extract inhibited macrophage activation and APC function, and indirectly suppressed T-cell activation 58). Other stable [6]-gingerol metabolites or analogs were reported to suppress LPS-induced NO production in murine macrophages mainly by reducing inos gene and iNOS protein production (Aktan et al. 2006). Some of ginger’s anti-inflammatory effects appear to be associated with decreased IκBα degradation and impaired nuclear factor κB (NF-κB) nuclear translocation of p65 59). The majority of scientific evidence does seem to suggest that ginger and its various components have anti-inflammatory effects both in vitro and ex vivo. However, the data supporting ginger as an effective anti-inflammatory agent in humans in vivo are still contradictory and incomplete.

Anti-Cancer Activities of Ginger

A great deal of interest by numerous research groups, including our own, is now being focused on the cancer-preventive and potential cancer therapeutic applications of ginger and its various components. Several aspects of the chemopreventive effects of numerous phytochemical dietary and medicinal substances, including ginger, have been reviewed previously 60), 61), 62), 63), 64), 65). Studies focused on the anticancer activities of various forms of ginger from a crude or partially purified extract to gingerols, especially [6]-gingerol; shogaols, especially [6]-shogaol; and zerumbone, a sesquiterpene compound derived from ginger and a number of minor components and metabolites. The effectiveness of ginger in preventing or suppressing cancer growth has been examined in a variety of cancer types, including lymphoma, hepatoma, colorectal cancer, breast cancer, skin cancer, liver cancer, and bladder cancer. The mechanisms proposed to explain the anticancer activities of ginger and its components include antioxidant activity and the ability to induce apoptosis, decrease proliferation, cause cell-cycle arrest, and suppress activator protein 1 (AP-1) and NF-κB/COX-2 signaling pathways (Figure 1).

Figure 1. The anticancer activities exerted by ginger.

anticancer activities of ginger
[Source 66)]

The anticancer activities of [6]-gingerol and zerumbone have been associated with their antioxidant activities. Several ginger components were reported to have effective anticancer promoter activity based on their ability to inhibit TPA-induced Epstein-Barr virus early antigen (EBV-EA) in Raji cells 67), 68). [6]-gingerol was reported to suppress the reactive oxygen species-potentiated invasive capacity of ascites hepatoma AH109A cells by reducing peroxide levels 69). In normal RL34 rat liver epithelial cells, zerumbone was found to induce glutathione S-transferase and the nuclear localization of the transcription factor Nrf2, which binds to the antioxidant response element (ARE) of phase II enzyme genes 70). Zerumbone potentiated the expression of several Nrf2/ARE-dependent phase II enzyme genes, including Y-glutamyl-cysteine synthetase, glutathione peroxidase, and hemeoxygenase-1 71). Others have reported that zerumbone decreases TPA-induced hydrogen peroxide formation and edema corresponding to enhanced levels of various antioxidant enzymes 72). These types of changes have been linked with lower 7,12-dimethylbenz[a]anthracene (DMBA)-initiated/TPA-promoted tumor incidence, number of tumors per mouse, and tumor volume 73).

Treatment of cultured ovarian cancer cells with [6]-shogaol caused a marked growth inhibition that was associated with suppression of NF-κB activation as well as the diminished secretion of angiogenic factors, VEGF and IL-8 74), suggesting a role for this compound in preventing angiogenesis in cancer. In contrast to most reports, dietary consumption of ginger (0.5% or 1.0%) did not suppress aberrant crypt foci (ACF) formation or reduce the number of crypts per ACF in DMH-treated rats compared to untreated control rats 75). Dietary ginger did not significantly change the proliferative or apoptotic indexes of the colonic crypt cells induced by DMH 76). In marked contrast to many studies, ginger extract was not able to inhibit the development of N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN)/N-methyl-N-nitrosourea (MNU)-induced bladder cancer in male Swiss mice. In fact, in BBN/MNU/2% ginger-treated mice, the incidence of grade 2 transitional cell carcinoma was increased 77), 78).

Cardiovascular and Other Disease-Preventive Effects of Ginger

In addition to its effects in relation to cancer, some evidence supports a protective role for ginger in cardiovascular function and a number of other disease conditions. Ginger has gained interest for its potential to treat various aspects of cardiovascular disease, and the in vitro and animal data supporting the anti-inflammatory, antioxidant, antiplatelet, hypotensive, and hypolipidemic effects of this condiment have been reviewed 79). However, human trials are less convincing and more investigations are needed 80). Caution when taking ginger and other herbal extracts has been suggested because of an apparent association of ginger with reported incidences of increased risk of bleeding following surgery 81), 82) or if taken with anticoagulant drugs such as warfarin 83). However, the data are not conclusive 84). At least one study indicates that ginger has no effect on blood pressure, heart rate, or coagulation parameters and does not interact with anticoagulant drugs such as warfarin 85). These findings were supported in a later study in which ginger was reported to have no effect on clotting status or the pharmacokinetics or pharmacodynamics of warfarin in healthy subjects 86). An aqueous ginger extract was reported to induce a dose-dependent decrease in arterial blood pressure in a variety of animal models 87).

At least one group found that administration or consumption of standardized ginger extract decreased aortic atherosclerotic lesion areas, plasma triglycerides and cholesterol, low-density lipoprotein (LDL)-associated lipid peroxides, and LDL aggregation in mice 88). In rabbits that were fed a high-cholesterol diet, administration of ginger extract resulted in a significant antihyperlipidemic effect and a lower degree of atherosclerosis compared to the group that was fed cholesterol alone 89). Importantly, ginger powder (3 g/day in 1-g capsule 3xd) significantly lowered lipid levels in volunteer patients in a double-blind, controlled clinical trial study 90). Triglyceride and cholesterol were substantially decreased as was LDL levels compared to placebo group. Notably, the high-density lipoprotein (HDL) level of the ginger group was higher than that of the placebo group, whereas the very-low-density lipoprotein (VLDL) level of the placebo group was higher than that of the ginger group 91). Dried ginger powder (0.1 g/kg BW, per oral administration [p.o.] for 75 days) significantly lowered (50%) the development of atheroma in the aorta and coronary arteries of rabbits that were fed cholesterol 92). This effect was associated with decreased lipid peroxidation and increased fibrinolytic activity with ginger, but blood lipid levels were not different from control animals 93). Another compound isolated from ginger, (E)-8 β,17-epoxylabd-12-ene-15,16-dial, was reported to inhibit cholesterol biosynthesis 94), and ginger meal (1%) decreased serum cholesterol levels significantly 95). Ginger was also reported to slightly reduce retinoid-binding protein mRNA expression levels in liver and visceral fat in male rats that were fed cholesterol to induce hyperlipidemia 96). These results hint that ginger consumption might improve lipid metabolism 97).

Benefits of Ginger

There’s some information from scientific studies suggest that ginger (Zingiber officinale) might have beneficial effects on nausea and vomiting associated with motion sickness, surgery, and pregnancy. However, much less is known about other uses of ginger for other health conditions.

Asthma is a chronic disease characterized by inflammation and hypersensitivity of airway smooth muscle cells to different substances that induce spasms, and ginger has been used for centuries in treating respiratory illnesses. Components of ginger rhizomes are reported to contain potent compounds capable of suppressing allergic reactions and might be useful for the treatment and prevention of allergic diseases 98). Ghayur et al. 99) reported that a ginger extract inhibits airway contraction and associated calcium signaling, possibly by blocking plasma membrane calcium channels. In a mouse model of Th2-mediated pulmonary inflammation, an intraperitoneal injection of a ginger extract mainly comprised of gingerols markedly decreased the recruitment of eosinophils to the lungs in ovalbumin-sensitized mice and also suppressed the Th2 cell-driven response to allergen 100).

Ginger has also been suggested to have antidiabetic effects. In the streptozotocin-induced diabetic rat model, rats that were fed ginger exhibited better glucose tolerance and higher serum insulin levels than untreated rats, suggesting that it can help control blood sugar levels 101). Treatment with a ginger extract produced a significant reduction in fructose-induced elevation in lipid levels, body weight, hyperglycemia, and hyperinsulinemia associated with insulin resistance 102). An aqueous extract of raw ginger (administered daily, 500 mg/kg intraperitoneally) to streptozotocin-induced diabetic rats lowered serum glucose, cholesterol, and triacylglycerol levels; decreased urine protein levels, water intake, and urine output; and prevented the weight loss associated with diabetes in this model 103).

Dried ginger may have beneficial effects in treating dementia, including Alzheimer’s disease 104). Ulcerative colitis is a chronically recurrent inflammatory bowel disease of unknown origin, and in rats, ginger extract alleviated the symptoms of acetic acid-induced ulcerative colitis 105).

Ginger and Gingerols

The oleoresin (i.e., oily resin) from the rhizomes (i.e., ginger roots) of ginger contains many bioactive components, such as [6]-gingerol (1-[4′-hydroxy-3′- methoxyphenyl]-5-hydroxy-3-decanone), which is the primary pungent ingredient that is believed to exert a variety of remarkable pharmacological and physiological activities 106). Gingerols possess the labile β-hydroxy keto functional group, which makes it susceptible to transformation to less-pungent compounds such as shogaols and zingerone by elevated temperature 107). Gingerols and shogaols have been reported to exhibit many interesting pharmacological and physiological functions, for example, immuno-modulatory, anti-tumorigenic, anti-inflammatory, anti-apoptotic, anti-hyperglycemic, anti-lipidemic, anti-pyretic, cardiotonic, chemopreventive, anti-inflammatory, cancer preventive properties and antioxidant properties 108), 109), 110), 111). It has been reported that ginger extract inhibits the production of nitric oxide (NO) and proinflammatory cytokines in lipopolysaccharide (LPS)-stimulated BV-2 microglial cells via the NF-κB (nuclear factor kappa-light-chain-enhancer of activated B cells) pathway 112). An inhibitory effect by 6-gingerol was shown on the production of proinflammatory cytokines in murine peritoneal macrophages 113). Likewise, 6-shogaol has been shown to inhibit LPS-induced inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX) gene expression in macrophages.14 Moreover, 6-shogaol showed significant neuroprotective effects in vivo in transient global ischemia via the inhibition of microglia. It suppressed the microglial activation induced by LPS both in primary cortical neuron-glia culture and in an in vivo neuroinflammatory model 114). In vitro data have shown that ginger’s active principles protect nerve cells and may have potential in the treatment of Alzheimer’s disease 115). This study 116) shows that ginger phytochemicals targets such as AChE, BuChE, COX-1, COX-2, JNK, and NOS, have already been verified by experiments for their inhibition by ginger extracts; it is being proposed that 1,3-diacetoxy derivative (compound 7) binds to the AChE active site with certain orientation and conformation so that it may act as an inhibitor of that enzyme. This study provides important information for optimizing lead compounds of ginger for the treatment of Alzheimer’s disease 117).

Ginger for Pregnancy-induced nausea and vomiting

A review of four randomised clinical trials 118), all trials found orally administered ginger to be significantly more effective than placebo in reducing the frequency of vomiting and intensity of nausea in pregnancy. The authors concluded that the best available evidence suggests that ginger is a safe and effective treatment for pregnancy related nausea and vomiting. However, there remains uncertainty regarding the maximum safe dosage of ginger, appropriate duration of treatment, consequences of over-dosage, and potential drug-herb interactions; all of which are important areas for future research 119).

Another study on ginger and its safety for use during pregnancy 120) involving 1,020 Norwegian women who reported using ginger during pregnancy. The study found no evidence that using ginger during pregnancy was not associated with any increased risk of congenital malformations. No increased risk for stillbirth/perinatal death, preterm birth, low birth weight, or low Apgar score was detected for the women exposed to ginger during pregnancy compared to women who had not been exposed. This finding is clinically important for health care professionals giving advice to pregnant women with pregnancy-induced nausea and vomiting 121).

Ginger and Osteoarthritis

Osteoarthritis (OA) is a degenerative joint disease, which is associated with increased pain and disability, and a simultaneous decline in the quality of life of sufferers. While there is no cure for osteoarthritis, there are numerous treatments that aim to reduce sufferers’ symptoms and disability, and improve their quality of life. Medications, which have long been integral interventions for the management of osteoarthritis, have recently been found to cause harm in some patients. Simultaneously, the increasing recognition of complementary and alternative therapies as part of mainstream health care, has seen many sufferers of osteoarthritis use these therapies. Ginger has been commonly prescribed by herbalists for sufferers of osteoarthritis due to its anti-inflammatory and circulatory stimulant effects 122).

A systematic review was to evaluate the safety and effectiveness of ginger in adults with osteoarthritis 123). For changes in pain severity, studies comparing ginger extract (n = 110) to placebo (n = 111) reported mixed findings in support of the use of Ginger. Studies comparing ginger to an active control found participants who received Ibuprofen (n = 96) had a greater change in median pain intensity compared with participants who received Ginger (n = 110), and while findings were statistically significant for only one of the two studies, the results had limited clinical significance. Similarly, while two placebo-controlled studies reported differences between ginger (n = 70) and placebo (n = 71) for changes in disability and functional capacity, the difference was statistically and clinically significant for only one study. In one study comparing ginger to an active control, participants receiving Ibuprofen (n = 56) reported a statistically significant improvement in disability and functional capacity over time when compared with participants receiving Ginger (n = 56). In terms of safety, Ginger was well tolerated when compared with Ibuprofen, with infrequent reports of mild, and predominantly gastrointestinal, adverse effects.

Conclusion of the systematic review: Current evidence is weak for the use of ginger in adults with osteoarthritis of the knee and/or hip 124). Much of this can be attributed to significant heterogeneity between studies. Improvements in research design, instrumentation and ginger dosage, which more closely reflect current clinical practice, may help to demonstrate the safe and effective use of ginger in osteoarthritis sufferers.

Ginger for treating primary Dysmenorrhoea (painful menstruation, typically involving abdominal cramps)

A systematic review was to evaluate the use of ginger in alleviating symptoms of primary dysmenorrhea 125), the review authors conclusion based on four randomised clinical trials, there suggestive evidence for the effectiveness of 750–2000 mg ginger powder during the first 3–4 days of menstrual cycle for primary dysmenorrhea 126).

Ginger Helps Reduce Nausea from Chemotherapy

According to the National Cancer Institute 127) ginger helped prevent or reduce chemotherapy-induced nausea when taken with traditional anti-nausea drugs by patients with cancer, researchers have found. The results are from a randomized, double-blind, placebo-controlled clinical trial, the largest study to examine the potential effects of ginger on chemotherapy-related nausea 128).

Dr. Ryan and colleagues conducted a multisite randomized trial to assess the efficacy of ginger for chemotherapy-related nausea in cancer patients at member sites of the University of Rochester–affiliated Community Clinical Oncology Program 129). The participants consisted of 644 primarily female patients (90%) who were receiving chemotherapy for breast, digestive, lung, or other cancers. These patients were randomly assigned to receive a placebo or one of three doses of ginger (0.5 g, 1.0 g, or 1.5 g)  in capsule form which was divided into 2 doses given each day for 6 days, including 3 days leading up to the first day of chemotherapy and 2 days after chemotherapy began. Breast cancer was the most common type of malignancy among the participants (66%), followed by alimentary (6.5%) and lung (6.1%) cancers.

Patients who had experienced nausea following any chemotherapy cycle and who were scheduled to receive at least 3 additional treatment cycles were eligible to participate in the study. All of the patients also received traditional anti-nausea medications during the study, 5-HT3 receptor antagonist antiemetics — ondansetron (Zofran) or granisetron (Kytril) — starting on day 1 of all cycles and began supplementation with either ginger or placebo 3 days before the first day of a chemotherapy cycle.

Patients rated their nausea four times per day on a scale of 1 to 7. The degree of nausea experienced was rated at various times during the first 4 days of each chemotherapy cycle.

Their results showed that all doses of ginger significantly reduced nausea more than the placebo, with the 0.5 g and 1.0 g doses having the greatest effect. That dose is the equivalent of 1/4 to 1/2 a teaspoon of ground ginger, Dr. Ryan added 130).

Patients using ginger rated their nausea 1, which is none at all, or 2, which is slight nausea, said Dr. Ryan, while the placebo group rated their nausea 4, which is extremely nauseated.

Dr. Ryan speculates that the highest dose (1.5 gram) might not have worked as well as the lower doses because they may have reached the saturation point with the lower doses. She also could not speculate whether food products that contain ginger, such as cookies and tea, would have the same effect. “If they contain the same amount of ginger, then it’s possible,” she said. “But my guess is that a lot of them just use ginger flavoring, not real ginger. And they may also contain ingredients like sugar, which could affect the efficacy.”

The researchers concluded each dose of ginger was more effective than the placebo at mitigating nausea. The most effective doses were either 0.5 g or 1.0 g, taken during the first day of chemotherapy. Effectiveness decreased linearly over a 24-hour period. The highest dose (1.5 gram) may not be as effective, the researchers speculated, because it is more than the maximum absorption dose for biological activity 131). Reduced nausea will improve cancer patient quality of life during chemotherapy.

In another study using ginger root powder as an anti-emetic and an add-on therapy in children and young adults receiving high emetogenic chemotherapy 132). Acute chemotherapy-induced nausea and vomiting was defined as nausea and vomiting occurring within 24 hr of start of chemotherapy (days 1-4) and delayed chemotherapy-induced nausea and vomiting as that occurring after 24 hr of completion of chemotherapy (days 5-10). Sixty chemotherapy cycles of cisplatin/doxorubicin in bone sarcoma patients were randomized to ginger root powder capsules or placebo capsules as an additional antiemetic to ondensetron and dexamethasone in a double-blind design. The results were acute moderate to severe nausea was observed in 28/30 (93.3%) cycles in control group as compared to 15/27 (55.6%) cycles in experimental group (those receiving ginger root powder). Acute moderate to severe vomiting was significantly more in the control group compared to the experimental group [23/30 (76.7%) vs. 9/27 (33.33%) respectively. Delayed moderate to severe nausea was observed in 22/30 (73.3%) cycles in the control group as compared to 7/27 (25.9%) in the experimental group. Delayed moderate to severe vomiting was significantly more in the control group compared to the experimental group [14/30 (46.67%) vs. 4/27 (14.81%). The study concluded that ginger root powder was effective in reducing severity of acute and delayed chemotherapy-induced nausea and vomiting as additional therapy to ondensetron and dexamethasone in patients receiving high emetogenic chemotherapy 133).

Ginger Side Effects

Ginger, when used as a spice, is believed to be generally safe 134), 135).

Observational studies in humans suggest no evidence of teratogenicity from treatments for early pregnancy nausea that included ginger 136). These results were confirmed in a similar trial showing that administration of ginger beginning at the first trimester of pregnancy did not appear to increase the rates of major malformations above the baseline rate of 1-3% 137). Overall, these data indicate that ginger consumption appears to be very safe with very limited side effects.

In some people, ginger can have mild side effects such as abdominal discomfort, heartburn, diarrhea, and gas.

Some experts recommend that people with gallstone disease use caution with ginger because it may increase the flow of bile.

Research has not definitely shown whether ginger interacts with medications, but concerns have been raised that it might interact with anticoagulants (blood thinners).

Although several studies have found no evidence of harm from taking ginger during pregnancy, it’s uncertain whether ginger is always safe for pregnant women. If you’re considering using ginger while you’re pregnant, consult your health care provider.

Summary

Ginger is not only an extremely popular dietary condiment used for flavoring food but also an herb that has been used for thousands of years as a medicinal herb to treat a variety of ailments. Chemical and metabolic analyses have revealed that ginger comprises hundreds of compounds and metabolites. The most extensively studied bioactive components include gingerols and shogaols, especially 6-gingerol and 6-shogaol, respectively. The content of each component is clearly dependent on the source and preparation of the ginger rhizome. Research interest in determining the role of natural compounds in preventing disease has increased markedly over the last few years. In spite of the abundance of research studies, many of the results are phenomenon based and provide data that are descriptive and observational on laboratory animals. More studies are needed humans on the kinetics of ginger and its constituents and on the effects of consumption over a long period of time. Specific molecular targets and mechanisms of action need to be identified. Ginger clearly has a vast number of components and metabolites, many of which have not been studied in detail. The lack of standardization of ginger supplements is disconcerting, and whether consumption of high levels of isolated components (e.g., 6-gingerol) is advisable is uncertain. 6-gingerol or other ginger components might require inter-reactivity or dependency on other components in the whole food source to exert their positive effects 138).

References   [ + ]

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