green coffee beans

Does green coffee bean extract help in weight loss?

Pawel Malczewski
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Short summary:

Even though most of the studies show promising results, there is no sufficient evidence that green coffee extract (GCE), with its main active ingredient chlorogenic acid, has weight loss effects.

The reason for a lack of strong evidence is that most of these studies were sponsored by companies producing GCE and therefore are biased. These studies were small and had some flaws in the methods that were used.

Chlorogenic acid (and therefore GCE) can potentially prove to be effective in weight loss. However, more good quality and larger studies are needed. For a quick answer click here.

Explanation

The purpose of creating a green coffee extract was to produce a supplement containing a high level of and concentrated chlorogenic acid, which is believed to have various health properties including widely claimed weight loss properties.

The weight loss properties of these products usually come from the information on the products themselves, from scientific studies which are mostly biased (since they are sponsored by the industry) and from anecdotal evidence (which could also be initiated by the industry).

Green (raw) coffee beans are the best source of chlorogenic acid and the best way to obtain it is by extracting it.
Note: these products can contain caffeine, however decaffeinated types are also available.

There are other ways of obtaining chlorogenic acid but GCE supplements seem to be the best option. Brewing green beans produces an awful tasting beverage and roasting beans drastically reduces the amount of chlorogenic acid. (read more..)

What do studies show on the effectiveness of chlorogenic acid in weight loss?

A recent systematic review from 2011 (a study that combined all of the available studies and used statistics to calculate the overall results) concluded that all studies regarding the GCE might have been industry bias, and the methodology of these studies had poor quality.

More independent and high quality studies are needed to show if GCE or chlorogenic acid are effective in weight loss. (1)Onakpoya I, Terry R, Ernst E. The use of green coffee extract as a weight loss supplement: a systematic review and meta-analysis of randomised clinical trials. Gastroenterol Res Pract. 2011;2011. pii: 382852. Available here.

One study, for instance, which showed significant weight loss in overweight people taking GCE has been retracted by the authors with the reason that “The sponsors of the study cannot assure the validity of the data”. (2)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. STUDY RETRACTED. Diabetes Metab Syndr Obes. 2012; 5: 21–27. Available here.

Two studies from 2007, with no reported conflict of interest, showed that chlorogenic acid reduces weight when consumed as an addition to instant coffee. This effect is attributed to the decrease of glucose absorption.

The first study, using 12 participants, showed that when chlorogenic acid is mixed with instant coffee it shows a 6.9% reduction in glucose absorption compared to when instant coffee is taken on its own.

The second study, using 30 overweight participants, showed that overweight people who had chlorogenic acid added to coffee, lost 3 times more weight over a 3 month period than those that had only instant coffee. (3)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 Nov-Dec;35(6):900-8. Available here.

There are also some rat and mice studies which have shown that chlorogenic acid may reduce fat accumulation and prevent weight gain. (4)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 Mar 17;6:9. Available here. (5)Cho AS, Jeon SM, Kim MJ, Yeo J, Seo KI, Choi MS, Lee MK. Chlorogenic acid exhibits anti-obesity property and improves lipid metabolism in high-fat diet-induced-obese mice. Food Chem Toxicol. 2010 Mar;48(3):937-43. Available here.

More studies, with wider samples and independent from the industry, are needed.

Conclusion

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It is possible, although not proven, that chlorogenic acid and therefore green coffee extract may aid in weight loss.

There are other, more reliable methods of weight loss such as a balanced low carb diet and exercise.

However, when deciding to start taking GCE for this purpose, you need to consider that the long term effects of this supplement have not yet been thoroughly investigated.

References   [ + ]

1. Onakpoya I, Terry R, Ernst E. The use of green coffee extract as a weight loss supplement: a systematic review and meta-analysis of randomised clinical trials. Gastroenterol Res Pract. 2011;2011. pii: 382852. Available here.
2. 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. STUDY RETRACTED. Diabetes Metab Syndr Obes. 2012; 5: 21–27. Available here.
3. 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 Nov-Dec;35(6):900-8. Available here.
4. 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 Mar 17;6:9. Available here.
5. Cho AS, Jeon SM, Kim MJ, Yeo J, Seo KI, Choi MS, Lee MK. Chlorogenic acid exhibits anti-obesity property and improves lipid metabolism in high-fat diet-induced-obese mice. Food Chem Toxicol. 2010 Mar;48(3):937-43. Available here.

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