Our proprietary “Star-Rating” system was developed to help you easily understand the amount of scientific support behind each supplement in relation to a specific health condition. While there is no way to predict whether a vitamin, mineral, or herb will successfully treat or prevent associated health conditions, our unique ratings tell you how well these supplements are understood by the medical community, and whether studies have found them to be effective for other people.
For over a decade, our team has combed through thousands of research articles published in reputable journals. To help you make educated decisions, and to better understand controversial or confusing supplements, our medical experts have digested the science into these three easy-to-follow ratings. We hope this provides you with a helpful resource to make informed decisions towards your health and well-being.
3 Stars Reliable and relatively consistent scientific data showing a substantial health benefit.
2 Stars Contradictory, insufficient, or preliminary studies suggesting a health benefit or minimal health benefit.
1 Star For an herb, supported by traditional use but minimal or no scientific evidence. For a supplement, little scientific support.
Extracts providing at least 50 mg per day chlorogenic acids
Extracts of green, unroasted coffee that are high in chlorogenic acids might help lower blood pressure.
While drinking regular coffee or other sources of caffeine may slightly raise blood pressure,1 coffee also contains chlorogenic acids that may have a blood pressure–lowering effect, according to animal research.2 However, a double-blind study found that a substance produced by roasting coffee can inhibit this blood pressure–lowering effect, and by removing this substance, coffee lowered blood pressure.3 This suggests that extracts of unroasted (“green”) coffee that are high in chlorogenic acids might help lower blood pressure. A double-blind trial found that eating soups containing green coffee extracts providing at least 50 mg per day chlorogenic acids lowered blood pressure significantly better than soup containing no green coffee extracts in people with mild hypertension, but that lower amounts of green coffee extracts in the soup were not effective.4 A double-blind trial of green coffee extract supplements containing 140 mg per day of chlorogenic acids reduced systolic blood pressure by an average of 10 mm Hg and diastolic blood pressure by an average of 7 mm Hg in people with mild hypertension.5 One controlled trial found no blood pressure–lowering effect of green coffee extract supplements in people with normal blood pressure.6
Extract providing 400 to 450 mg of chlorogenic acids per day
Some controlled research has suggested that green coffee extracts taken as supplements or in food may support weight loss.
Animal research suggests that green coffee extract and its major component, chlorogenic acid, may help with weight loss and reducing abdominal fat.7 , 8 An uncontrolled human study found that people who drank 750 ml per day of coffee containing green coffee bean constituents for four weeks ate fewer calories and lost weight.9 In a controlled study, overweight people who drank a coffee beverage containing green coffee extract (providing 400 to 450 mg of chlorogenic acids per day) for 12 weeks lost an average of about 12 pounds and 3.6% body fat compared to less than 4 pounds and an insignificant amount of body fat lost by people who drank a similar amount of coffee without added green coffee extracts.10 Another controlled study reported a statistically significant 11 pound weight loss after 60 days when overweight people took 400 mg per day of green coffee extracts (providing 180 mg of chlorogenic acids per day), compared to about a five pound loss in people taking a placebo.11 The green coffee extracts group also significantly raised their ratio of lean body tissue to body fat compared to the control group. In a double-blind trial, overweight adults who took daily amounts of either 700 or 1,050 mg of green coffee extracts (providing 320 to 480 mg chlorogenic acids) for six weeks lost an average of almost 18 pounds and over 4% body fat, a statistically significant improvement compared to when they took a placebo.12 Since all of these studies lasted only 12 weeks or less, more research is needed to determine if green coffee extracts can help people accomplish long-term weight loss.
Type 2 Diabetes
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Drinking either regular or decaffeinated coffee has been associated with reduced type 2 diabetes risk in several preliminary human studies.
Drinking either regular or decaffeinated coffee has been associated with reduced type 2 diabetes risk in several preliminary human studies.13 Test tube studies suggest that chlorogenic acid, a primary constituent found in both coffee and in green coffee extract may inhibit glucose production by the liver,14 which could theoretically lead to lower blood sugar. An animal study found that green coffee extract also prevented the reduction in insulin sensitivity caused by a high-fat diet.15 No human studies have tested the effect of green coffee extract on reducing risk of diabetes or improving insulin sensitivity, but a double-blind trial found that healthy people who drank a sweetened coffee beverage containing green coffee extract (providing 400 to 450 mg of chlorogenic acids) had lower blood sugar during the following two hours compared to when they drank the same coffee beverage without added green coffee extract.16 More research is needed to determine whether green coffee extract can help prevent or treat type 2 diabetes.
1. Noordzij M, Uiterwaal CS, Arends LR, et al. Blood pressure response to chronic intake of coffee and caffeine: a meta-analysis of randomized controlled trials. J Hypertens 2005;23:921-8 [review].
2. Noordzij M, Uiterwaal CS, Arends LR, et al. Blood pressure response to chronic intake of coffee and caffeine: a meta-analysis of randomized controlled trials. J Hypertens 2005;23:921-8 [review].
3. Yamaguchi T, Chikama A, Mori K, et al. Hydroxyhydroquinone-free coffee: a double-blind, randomized controlled dose-response study of blood pressure. Nutr Metab Cardiovasc Dis 2008;18:408-14.
4. Kozuma K, Tsuchiya S, Kohori J, et al. Antihypertensive effect of green coffee bean extract on mildly hypertensive subjects. Hypertens Res 2005;28:711-8.
5. Watanabe T, Arai Y, Mitsui Y, et al. The blood pressure-lowering effect and safety of chlorogenic acid from green coffee bean extract in essential hypertension. Clin Exp Hypertens 2006;28:439-49.
6. Ochiai R, Jokura H, Suzuki A, et al. Green coffee bean extract improves human vasoreactivity. Hypertens Res 2004;27:731-7.
7. Cho AS, Jeon SM, Kim MJ, et al. Chlorogenic acid exhibits anti-obesity property and improves lipid metabolism in high-fat diet-induced-obese mice. Food Chem Toxicol 2010;48:937-43.
8. Shimoda H, Seki E, Aitani M. Inhibitory effect of green coffee bean extract on fat accumulation and body weight gain in mice. BMC Complement Altern Med 2006;6:9.
9. Bakuradze T, Boehm N, Janzowski C, et al. Antioxidant-rich coffee reduces DNA damage, elevates glutathione status and contributes to weight control: results from an intervention study. Mol Nutr Food Res 2011;55:793-7
10. Thom E. The effect of chlorogenic acid enriched coffee on glucose absorption in healthy volunteers and its effect on body mass when used long-term in overweight and obese people J Int Med Res 2007;35:900-8.
11. Dellalibera O. Lemaire B, Lafay S. Svetol, green coffee extract, induces weight loss and increases the lean to fat mass ratio in volunteers with overweight problem. Phytotherapie 2006;4:194–7.
12. Vinson JA, Burnham BR, Nagendran MV. Randomized, double-blind, placebo-controlled, linear dose, crossover study to evaluate the efficacy and safety of a green coffee bean extract in overweight subjects. Diabetes Metab Syndr Obes 2012;5:21-7.
13. Huxley R, Lee CM, Barzi F, et al. Coffee, decaffeinated coffee, and tea consumption in relation to incident type 2 diabetes mellitus: a systematic review with meta-analysis. Arch Intern Med 2009;169:2053–63 [review].
14. Henry-Vitrac C, Ibarra A, Roller M. Contribution of chlorogenic acids to the inhibition of human hepatic glucose-6-phosphatase activity in vitro by Svetol, a standardized decaffeinated green coffee extract. J Agric Food Chem 2010;58:4141-4.
15. Ho L, Varghese M, Wang J, et al. Dietary supplementation with decaffeinated green coffee improves diet-induced insulin resistance and brain energy metabolism in mice. Nutr Neurosci 2012;15:37-45.
16. Thom E. The effect of chlorogenic acid enriched coffee on glucose absorption in healthy volunteers and its effect on body mass when used long-term in overweight and obese people J Int Med Res 2007;35:900-8.
17. Alonso-Salces RM, Serra F, Reniero F, Héberger K. Botanical and geographical characterization of green coffee (Coffea arabica and Coffea canephora): chemometric evaluation of phenolic and methylxanthine contents. J Agric Food Chem 2009;57:4224-35.
18. Farah A, Monteiro M, Donangelo CM, Lafay S. Chlorogenic acids from green coffee extract are highly bioavailable in humans. J Nutr 2008;138:2309-15.
19. Iwai K, Kishimoto N, Kakino Y, et al. In vitro antioxidative effects and tyrosinase inhibitory activities of seven hydroxycinnamoyl derivatives in green coffee beans. J Agric Food Chem 2004;52:4893-8.
20. Glei M, Kirmse A, Habermann N, et al. Bread enriched with green coffee extract has chemoprotective and antigenotoxic activities in human cells. Nutr Cancer 2006;56:182-92.
21. Del Rio D, Stalmach A, Calani L, Crozier A. Bioavailability of coffee chlorogenic acids and green tea flavan-3-ols. Nutrients 2010;2:820-33 [review].
22. Ochiai R, Jokura H, Suzuki A, et al. Green coffee bean extract improves human vasoreactivity. Hypertens Res 2004;27:731-7.
23. Zhao Y, Wang J, Ballevre O, et al. Antihypertensive effects and mechanisms of chlorogenic acids. Hypertens Res 2012;35:370-4 [review].
24. Cho AS, Jeon SM, Kim MJ, et al. Chlorogenic acid exhibits anti-obesity property and improves lipid metabolism in high-fat diet-induced-obese mice. Food Chem Toxicol 2010;48:937-43.
25. Yamaguchi T, Chikama A, Mori K, et al. Hydroxyhydroquinone-free coffee: a double-blind, randomized controlled dose-response study of blood pressure. Nutr Metab Cardiovasc Dis 2008;18:408-14.
Last Review: 05-01-2013
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The information presented in Aisle7 is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications. Information expires June 2014.
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