Green Coffee Bean Claims Are Hard to Swallow, So Don’t Get Too Jazzed Up

green coffee beans on vine There’s been a lot of buzz about green coffee bean extract. But it’s disheartening for me to see yet another diet pill get so much press — including the recent love fest on the Dr. Oz show. Green Coffee Beans have emerged as the new Raspberry Ketones — similarly described by Dr. Oz as a “miracle pill that can burn fat”  and a “magic cure for weight loss.”   Once again, an endorsement by Dr. Oz seems to set off a fire-storm with companies scurrying to bottle this miracle and set up  websites to sell it– often using photos and quotes from Dr. Oz  himself.  There’s even a OzGreenCoffee page on Facebook.

green coffee beans

So how did this new frenzy get started?  Like many of today’s popular dietary supplements, there’s a small study (often paid for by the pill manufacturer) that gets the ball rolling.  That’s exactly what happened with Green Coffee Beans.  All of the recent claims are based on a single study of 16 people conducted in India.  The lead author is Joe Vinson, a chemist at the University of Scranton, Pennsylvania, who has conducted other studies examining polyphenols and other natural compounds in foods.  Funded by the supplement manufacturer Applied Food Sciences in Texas, the study was published in the online journal Diabetes, Metabolic Syndrome and Obesity: Targets and Therapy; you can read the full paper here.

Science-Based Medicine does an excellent job of analyzing the study in the post:  Dr. Oz and Green Coffee Beans – More Weight Loss Pseudoscience.  Author Scott Gavura concludes that the study has some serious methodological problems including the small sample size, lack of proper blinding, doses, unreliable diet recalls, and repeated measurements. The study was also not registered at, according to Scott Gavura, which he believes is a red flag.

Many medical journals will now refuse to publish a trial if it was not initially entered into a public registry. Not only does a registry ensure that negative results don’t disappear, it gives valuable information about the study, including its design, entry criteria, and who gave formal ethics approval for the study….I find it hard to believe that any investigator would undertake a clinical trial of an unproven supplement without obtaining prior ethics approval — but that seems to be the case.

Like many of today’s popular dietary supplements, including weight loss pills, there’s typically a small nugget of truth buried beneath all the hype.  Often preliminary studies do indicate a “suggestion” or the possibility a natural compound could have potentially beneficial effects in the body.  That appears to be the case with green coffee beans, which are rich in a type of polyphenol called chlorogenic acid (the purported active ingredient in the supplements). Historically, there’s been some research to suggest that regular coffee intake is linked to a healthier body weight, possibly due to the caffeine or the polyphenol content in the drink. That lead to this 2011 review paper on green coffee extract or GCE by Igho Onakpoya and colleagues (funded by GlaxoSmithKline) that explored the efficacy of GCE as a weight loss supplement.  The authors identified five clinical trials, although only three studies (published in 2006, 2007 and 2009) met the quality criteria for the review. However, all of the studies, the authors indicated, were associated with a high risk of bias. They concluded:

The evidence from RCTs (randomized clinical trials) seems to indicate that the intake of GCE can promote weight loss.  However, several caveats exist.  The size of the effect is small, and the clinical relevance of this effect is uncertain.  More rigorous trials with longer duration are needed to assess the efficacy and safety of GCE as a weight loss supplement.

Other experts have expressed their concern about popping green coffee bean extract, including these two physicians who were interviewed about the Vinson study by the LA Times:

Dr. Gerald Weissmann, a physician and biochemist at New York University:

This is certainly a provocative study, but nutrition experts would want assurances that green coffee beans do not cause malabsorption within the human gut — a condition that would lead to weight loss as well as malnutrition, heart arrhythmias and other problems because vitamins and minerals are not passing through the intestines.

Dr. Arthur Grollman, a pharmacologist at the State University of New York at Stony Brook

Coffee beans contain about 250 different chemicals — some with positive and others with negative effects on human health. Though Vinson identified polyphenols and chlorogenic acid as the agents that appear to promote weight loss, that claim needs further study.  In the meantime, consuming an extract that contains both good and bad chemicals in dense concentration seems an unwise thing to do.

Chlorogenic acid is found naturally in raw or green coffee beans, yet the supplement marketers claim that roasting destroys this beneficial compound. That’s why you need to buy it in pill form. Yet, Scott Gavura of Science-Based Medicine says that’s not true. He cites this study that shows chlorogenic acid is also present in roasted coffee and black tea

So is it a bad thing to buy green coffee bean extract? What’s the harm? I wouldn’t recommend for several reasons: First, all the promoters make a big deal about how participants in the study lost 17 pounds without making any changes in their eating or activity. All they did was take the pill. For sustainable weight management, it does come down to your daily habits, not relying on a pill to help you meet your goal. You can’t just take a supplement and then ignore what you eat and don’t make an effort to be more active. And if you don’t get the miraculous results — like the woman on Dr. Oz’s show who lost a 1 pound a day for 5 days — then you feel like a failure and you’re then seeking the next big miracle pill. It’s a never-ending cycle. And it’s money in your pocket that you could be spending on real food.

Yes, maybe there’s a biological effect due to chlorogenic acid. Lots of natural compounds in food go to work in different ways once we eat them. But the effect on our weight is likely very small. There are so many other things that we could be doing that would make such a bigger impact — such as eating more fruits and vegetables each day, keeping sight of portions, increasing our activity, and even enjoying coffee (in a cup instead of a pill).

Images courtesy of rareeyes21 and Rich Private Label Nutraceuticals

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