Dietribes / Flavour of the Week

Green Coffee Bean Extract – Hype vs. Evidence


flavour-of-the-week-logo3Admittedly, we were kind of waiting this one out. Waiting for the fervor to die down and another botanical weight loss agent endorsed, leaving green coffee bean extract – much like raspberry ketones – as just another quick-lived, limited-evidence fad supplements. But at eight-months post-Dr. Oz endorsement, this one seems to have some staying power… and there might even be some legitimate human trials out there to support this product?

Could [green coffee bean extract] be a tool in the tool box for weight loss? Potentially, but we don’t have enough information to say that,” says registered dietitian Andrea N. Giancoli, spokesperson for the Academy of Nutrition and Dietetics.

Well, this sounds interesting; equivocal, but interesting…

What is green coffee bean extract? The name says it all! Green coffee bean extract comes from unroasted coffee beans, which keeps the active ingredient, chlorogenic acid, intact (it is greatly reduced in the roasting process). Green coffee bean extract also contains caffeine (though most is removed in processing) and chlorogenic-related compounds like neochlorogenic acid and feruloylquinic acid (1).

What are the claims? The primary claim is weight loss, though other claims include blood sugar control and improvements in hypertension. While exact mechanisms are unknown, with respect to weight loss the evidence from animal models suggests that chlorogenic acid and its metabolites may affect how the body metabolizes carbohydrates (2).

What does the research say? Unlike raspberry ketones, which were endorsed by *you know who* with only in vitro and in vivo studies as evidence, green coffee bean extract has been tested in people… and in RCTs (albeit, small ones) to boot! Interestingly, some of the most promising results relate to hypertension, particularly those with mild hypertension, though only two clinical trials have been published to-date (3,4).

The explosion in green coffee bean extract sales earlier this year has little to do with hypertension though; sales stem from an Indian study published in January 2012 suggesting green coffee bean extract is a useful weight loss supplement. Vinson et al. (5) compared high-dose green coffee bean extract (350 mg three times daily) with a low-dose supplement (350 mg twice daily) and placebo in a 22-week cross-over weight loss trial (click here for free full-text). Each supplement trial lasted for six-weeks with a two-week washout period in between. The study was small (n = 16) and included young, overweight individuals (mean BMI = 28.2).

While there were statistically significant changes in body weight, BMI and percentage body fat, it is hard to determine the clinical significance of this study. From our cursory look at their data, it appears that participants lost an average of 2.8% body weight in the high-dose group (mean loss = 2.0 kg) and 2.2% body weight in the low-dose group (mean loss = 1.5 kg); neither supplement group meets the oft-used 5% body weight reduction to be deemed a clinical treatment “success”. There is also no mention of a power analysis – would a study group of 16 really be enough to demonstrate a true difference (particularly given their multitude of statistical analyses), even with a cross-over design?

While the authors go on to “name-drop” a 2011 meta-analysis (6) as being “consistent” with their positive results, the meta-analysis involved only TWO studies and stated the following:

It is concluded that the results from these trials are promising, but the studies are all of poor methodological quality. More rigorous trials are needed to assess the usefulness of GCE as a weight loss tool. Onakpoya et al. (6)

No Baloney’s advice? As always… more trials are needed. While there are some interesting BUT very preliminary results, we certainly don’t think there is enough evidence to support the hoopla. Our biggest beef? That green coffee bean extract purveyors claim the supplement is effective WITHOUT changes to diet and exercise. Can you see the giant red flag?

While green coffee bean extract appears to be safe, no long-term data exists. Our advice is: drink your coffee or green tea (if you want to!), monitor your food intake, be mindful of portion size and satiety, and move your body more. The End.

References:

  1. Daglia M, Papetti A, Gregotti C. In vitro antioxidant and ex vivo protective activities of green and roasted coffee. J Agri Food Chem 2000; 48:1449-54.
  2. Johnston KL, Clifford MN, Morgan LM. Coffee acutely modifies gastrointestinal hormone secretion and glucose tolerance in humans: glycemic effects of chlorogenic acid and caffeine. Amer J Clin Nutr 2003; 78:728-33.
  3. Watanabe T, Arai Y, Mitsui Y, Kusaura T, Okawa W, Kajihara Y, Saito I. 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.
  4. Kozuma K, Tsuchiya S, Kohori J, Hase T, Tokimitsu I. Antihypertensive effect of green coffee bean extract on mildly hypertensive subjects. Hypertens Res 2005; 28:711-8.
  5. 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.
  6. 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; [epub ahead of print].
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2 thoughts on “Green Coffee Bean Extract – Hype vs. Evidence

  1. Pingback: Nutrition Newsmakers of 2012 | No Baloney

  2. Pingback: TGIF | No Baloney

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