Product Reviews
Green Coffee Bean Extract Supplements Review (for Weight Loss)

Reviewed and edited by Tod Cooperman, M.D. Tod Cooperman, M.D.
Initial Posting: 11/2/12 Updated 4/16/19
Green Coffee Bean Extract Supplements Reviewed by
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What It Is:
As the name implies, green coffee bean extract (or "green coffee extract") is an extract from raw, green coffee beans — the same beans which are used to make coffee if roasted. The extract contains substantial amounts of polyphenolic antioxidants known as chlorogenic acids (CGAs) — comprising as much as 50% of most extracts. It is these compounds which are believed to be important to the activity of green coffee extract in the body. The extract also naturally contains some caffeine, the amount of which may vary considerably across products (from about 1% to 10%), apparently depending on the extent to which the extract is decaffeinated.

What It Does:
The CGAs in green coffee bean extract appear to have a variety of effects, including a slight lowering blood of pressure (see the Encyclopedia article for more about this). However, it is most commonly promoted for weight loss (See Product Review of Weight Loss Supplements for information about other weight loss supplements). Two small, short-term studies (summarized below) using using a branded green coffee bean extract (Svetol®, Berkem/Naturex) have been performed in overweight individuals. Svetol is made from decaffeinated green coffee beans and contains 45% to 50% total CGAs (about one-third of which is the specific compound 5-caffeoylquinic acid (5-CGA), and less than 2% caffeine).

The studies showed a modest, but statistically significant, weight loss (roughly 3 lbs per month), among people taking green coffee bean extract. However, those receiving placebo also lost some weight (about 1 lb per month), so the additional weight loss from the extract appears to be about 2 lbs per month. The studies include the following:
  • 200 mg twice per day (400 mg per day) of extract (Svetol®) for 12 weeks showed a mean weight loss of 10.9 lbs (4.97 kg) vs. 5.4 lbs (2.45 kg) for placebo. Weight reduction was somewhat higher than in other studies as a bland, low-calorie diet given to both groups (Dellalibera, Phytotherapie 2007).
  • 200 mg daily of extract (Svetol®) added to instant coffee for 12 weeks showed a mean weight loss of 11.9 lbs (5.4 kg) vs. 3.7 lbs (1.69 kg) for placebo. (Thom, J Int Med Res 2007). Sugar (as glucose) was added to the coffee, but there was a 6.9% reduction in glucose absorption among those getting extract compared to those getting placebo.
A 2012 study using another green coffee bean extract, (GCA®, Applied Food Sciences) containing 45.9% total chlorogenic acids and 2 to 4% caffeine (Vinson, Diab, Met Synd and Obes, 2012), was subsequently retracted in 2014 by its authors who conceded that they could not assure the validity of the data. The retraction occurred as part of settlement of a lawsuit brought by the U.S. FTC against Applied Food Sciences, the manufacturer of the tested product, GCA®. The authors, from the University of Scranton, did not conduct the study but had accepted data from researchers in India who had performed the study with funding from Applied Food Sciences. The published study had reported statistically significant weight loss over 6 weeks using two different doses of GCA®. (See the Warnings about the lawsuits against Applied Food Sciences and Pure Green Coffee for more information.)

In addition, a very short-term study conducted by The Dr. Oz Show in 2012 involved giving 100 women 400 mg of a proprietary green coffee extract three times daily (30 minutes before each meal) or placebo. There were no special changes in diet or exercise. Over the two-week period of the study, those taking the extract reported a 2 lb weight loss versus a 1 lb loss among those taking placebo. It is interesting that the participants lost in just two weeks about the same amount of weight lost per month in published studies. A possible explanation is that more weight loss occurs during the initial weeks of treatment.

How It Works
Exactly how green coffee extract may work is not known. However, there is some evidence that it inhibits an enzyme (hepatic glucose-6-phosphatase), reducing glucose production and glucose levels — a potentially anti-diabetic effect (Henry-Vitac, J Ag Food Chem, 2010). This may force the body to use fats as energy, instead of glucose.

Quality Concerns and What CL Tested:
It is important that products contain the chlorogenic acids (CGAs) found in the types of green coffee bean extracts shown to work in clinical studies. As a manufacturer could potentially skimp on an ingredient or even add CGA compounds to a supplement without using actual green coffee extract, purchased several supplements sold in the U.S. and analyzed their chemical constituents, checking for specific and total CGAs, as well as caffeine levels. These amounts were expected to meet claimed amounts and, in the case of total CGAs, a minimum expected content of 45%. Products were also checked for potential contamination with lead and cadmium, heavy metals which can contaminate botanical products. (See How Products Were Evaluated for more information about testing.)

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