Green coffee

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green coffee

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 1. 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 2. Based on an animal study involving mice fed high fat diet 3, 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 3. 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. 4. 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 5. 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 2. In the mice fed high fat diet study 3, 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 6. 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 7. 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 8. The daily intake of chlorogenic acid in persons drinking coffee varies from 0.5 to 1 g 9. The traditional method of extraction of green coffee extract from green coffee bean, Coffea canephora robusta, involves the use of alcohol as a solvent 10. 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 10. 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 11. 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 12. 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 13.

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 14. 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) 15. 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 16. 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 17. 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 18. “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 18.

The Federal Trade Commission charged the defendants with false and unsupported advertising claims, including 18:

  • 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 18.

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

green coffee beans

Table 1. Polyphenols in foods

Polyphenol content
Source (serving size)By wt or volBy serving
mg/kg fresh wt (or mg/L)mg/serving
Hydroxybenzoic acids (2, 6)Blackberry (100 g)80–2708–27
    Protocatechuic acidRaspberry (100 g)60–1006–10
    Gallic acidBlack currant (100 g)40–1304–13
    p-Hydroxybenzoic acidStrawberry (200 g)20–904–18
Hydroxycinnamic acids (2, 5–7)Blueberry (100 g)2000–2200200–220
    Caffeic acidKiwi (100 g)600–100060–100
    Chlorogenic acid Cherry (200 g)180–115036–230
    Coumaric acidPlum (200 g)140–115028–230
    Ferulic acidAubergine (200 g)600–660120–132
    Sinapic acidApple (200 g)50–60010–120
Pear (200 g)15–6003–120
Chicory (200 g)200–50040–100
Artichoke (100 g)45045
Potato (200 g)100–19020–38
Corn flour (75 g)31023
Flour: wheat, rice, oat (75 g)70–905–7
Cider (200 mL)10–5002–100
Coffee (200 mL)350–175070–350
Anthocyanins (8–10)Aubergine (200 g)75001500
    CyanidinBlackberry (100 g)1000–4000100–400
    PelargonidinBlack currant (100 g)1300–4000130–400
    PeonidinBlueberry (100 g)250–500025–500
    DelphinidinBlack grape (200 g)300–750060–1500
    MalvidinCherry (200 g)350–450070–900
Rhubarb (100 g)2000200
Strawberry (200 g)150–75030–150
Red wine (100 mL)200–35020–35
Plum (200 g)20–2504–50
Red cabbage (200 g)25050
Flavonols (11–18)Yellow onion (100 g)350–120035–120
    QuercetinCurly kale (200 g)300–60060–120
    KaempferolLeek (200 g)30–2256–45
    MyricetinCherry tomato (200 g)15–2003–40
Broccoli (200 g)40–1008–20
Blueberry (100 g)30–1603–16
Black currant (100 g)30–703–7
Apricot (200 g)25–505–10
Apple (200 g)20–404–8
Beans, green or white (200 g)10–502–10
Black grape (200 g)15–403–8
Tomato (200 g)2–150.4–3.0
Black tea infusion (200 mL)30–456–9
Green tea infusion (200 mL)20–354–7
Red wine (100 mL)2–300.2–3
Flavones (11–12, 14, 18)Parsley (5 g)240–18501.2–9.2
    ApigeninCelery (200 g)20–1404–28
    LuteolinCapsicum pepper (100 g)5–100.5–1
Flavanones (19–21)Orange juice (200 mL)215–68540–140
    HesperetinGrapefruit juice (200 mL)100–65020–130
    NaringeninLemon juice (200 mL)50–30010–60
    Eriodictyol
Isoflavones (22–25)Soy flour (75 g)800–180060–135
    DaidzeinSoybeans, boiled (200 g)200–90040–180
    GenisteinMiso (100 g)250–90025–90
    GlyciteinTofu (100 g)80–7008–70
Tempeh (100 g)430–53043–53
Soy milk (200 mL)30–1756–35
Monomeric flavanols (6, 17, 26, 27)Chocolate (50 g)460–61023–30
    CatechinBeans (200 g)350–55070–110
    EpicatechinApricot (200 g)100–25020–50
Cherry (200 g)50–22010–44
Grape (200 g)30–1756–35
Peach (200 g)50–14010–28
Blackberry (100 g)13013
Apple (200 g)20–1204–24
Green tea (200 mL)100–80020–160
Black tea (200 mL)60–50012–100
Red wine (100 mL)80–3008–30
Cider (200 mL)408
[Source 15]

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 19. 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 20. 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 21. 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 22. Other studies have reported sucrose content for Robusta coffee of 4.05–7.05% (dry weight basis) 23. 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 24.

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% 20, while it ranges from 1.51 to 3.33% (dry weight basis) for Robusta 25. 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) 25, which is considerably higher than Arabica 20.

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 26. 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 27.

How effective is green coffee?

Coffee is one of the most widely consumable beverages around the globe nowadays 28. The most commercialized coffee species universally are Coffea arabica and Coffea canephora commonly known as arabica and robusta varieties 29. 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 30. Coffee is the principal source of bioactive compounds that mainly comprises alkaloids classified as methylxanthines (caffeine, theobromine and theophylline) and trigonelline 31 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) 32. Caffeine and theobromine are essentially found in coffee beans, tea leaves, cacao beans, cola nuts and mate leaves 33. 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 34.

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 35. 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 25. Differences in sucrose content are also linked to the degree of ripening, pre and post-harvest processing 22, as well as post-harvest processing 36.

Figure 2. Coffee alkaloids structures

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 37. 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 38. Theobromine also stimulates the central nervous system to a lower degree than caffeine 39, usually used as smooth muscle relaxant and also causes diuresis 40. 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 30 and anti-invasive activity against cancer cells 38.

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) 41. 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 34 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 42. However, the content of theobromine in coffee is considerably lower than caffeine and is hardly ever investigated 31.

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 43. 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 43.

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 7. 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 44. 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) 15. The daily intake of chlorogenic acid in persons drinking coffee varies from 0.5 to 1 g 9. The traditional method of extraction of green coffee extract from green coffee bean, Coffea canephora robusta, involves the use of alcohol as a solvent 10. 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 45. Consumption of coffee has also been shown to produce changes in several glycemic markers in older adults 46. 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 47. Green coffee extract has also been postulated to modify hormone secretion and glucose tolerance in humans 48. 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 49. 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 50. 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 51. 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 51, 52. 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 53. 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 10, the third trial did not report that the green coffee extract used was fortified with chlorogenic acid 52. This warrants further investigation.

The randomized clinical trials identified from a systematic review and meta-analysis of randomized clinical trials 54 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 52 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 55 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 56 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 57 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 58, decreasing glucose output in the liver 59, 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 60.

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 61. 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 61.

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.

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