Medicines Q&As
Q&A 417.1
What is the evidence that green coffee extract works to reduce
weight?
Prepared by UK Medicines Information (UKMi) pharmacists for NHS healthcare professionals
Before using this Q&A, read the disclaimer at www.ukmi.nhs.uk/activities/medicinesQAs/default.asp
Date prepared: March 2013
Background
Obesity has been increasing worldwide1, as has interest in pharmacological approaches to weight
management. A healthy diet and increased physical activity remain the mainstays of treatment, but
there are some licensed pharmaceutical options for promoting weight loss available on prescription
and over the counter in the UK2, but it would appear that many patients are turning to alternatives
such as herbal medicine or nutraceuticals. The market for nutraceuticals for weight loss is growing
worldwide, with one estimate suggesting that the global market will be worth over 350 billion dollars in
20143. Yet there is a general lack of robust, quality information on efficacy of nutraceutical and herbal
products.
Green coffee beans are those which have not yet been roasted 4. There has been a large amount of
press attention and hype about green coffee extract (GCE) as an aid to weight loss following several
celebrity endorsements and its appearance in magazines and TV shows such as the “Dr Oz” show in
the US4,5. Products containing GCE are being heavily marketed on the internet and in health food
shops throughout the UK.
Answer
Mechanism of action
The process of roasting coffee beans reduces the amount of chlorogenic acid contained within the
beans. It is thought that chlorogenic acid has modulatory effects on glucose metabolism. There is
some evidence from animal models that chlorogenic acid inhibits accumulation of fat and reduces the
absorption of glucose from the GI tract4.
Green coffee extracts contain caffeine in levels similar to roasted coffee. Caffeine is a methylxanthine
compound which stimulates the CNS, heart muscles, and blood pressure pressor centres. It exerts a
diuretic effect with water loss of an estimated 1.17ml per milligram of caffeine. This may contribute to
any weight loss effects of green coffee extract6. The stimulant nature of caffeine may also add to the
effect of GCE products, although some decaffeinated extracts are available on the market e.g. Svetol 7
Systematic Reviews
Onakpoya et al
One systematic review exists in the medical literature. This study included only randomized controlled
trials. The study identified three trials which met its criteria. The meta-analysis found a statistically
significant difference in weight between individuals administered GCE and placebo (-2.47kg 95% CI 4.23—0.72). Considerable heterogeneity was found between trials. This weight reduction is
considered by the authors to be moderate, with an uncertain clinical significance. One of the included
studies is unpublished8.
Clinical Trials
Dellalibera et al
This study looked allocated 50 volunteers to either placebo (n=20) or Svetol, a proprietory GCE
product in addition to a bland low calorie diet. After 60 days, a significant reduction of 4.97kg was
observed in the treatment group compared to the placebo group (p=0.001). This trial is limited by its
size and lack of blinding9.
Available through NICE Evidence Search at www.evidence.nhs.uk
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Medicines Q&As
Vinson et al
Since the systematic review described above, a further trial has been published in the literature. This
had a randomized, double-blind, placebo controlled crossover design but unfortunately is of a very
small size- 16 subjects in total. The included patients had an average BMI of 28.22kg/m2- considered
overweight in the UK. Randomisation and blinding techniques are not adequately described in the
study. The trial was 22 weeks long in total and found significant reductions in weight, BMI and
percentage body fat for both the high and low dose arms of the trial, but not the placebo group. An
average weight loss of over 8kg was found in this study, however, the small size and unclear blinding
of this trial limits its usefulness3.
Summary
Green coffee extract appears to exert most of its effect through chlorogenic acid, a constituent which
is mainly lost during the coffee roasting process. There is some limited evidence that green coffee
extract can contribute to modest weight loss compared to placebo. However, trials are currently
limited by their size and some methodological flaws.
Until more robust, larger clinical trials are undertaken, the true effects of green coffee extract are
difficult to quantify. Any benefits in weight loss will need to be weighed against the potential risks of
the product.
Limitations
This Medicines Q&A refers only to the efficacy of green coffee bean extract. For information on the
safety of such products, please refer to Medicines Q&A 418 “What are the safety concerns
surrounding use of green coffee extract for weight loss?”
Quality Assurance
Prepared by
Hayley Johnson, Regional Drug & Therapeutics Centre
Date Prepared
6th March 2013
Checked by
Hayley Sharpe, Regional Drug & Therapeutics Centre
Date of check
17th April 2013
Search strategy
Embase (green AND coffee AND extract).af [Limit to: Human]
AND
Weight reduction/
Medline (green AND coffee AND extract).af [Limit to: Humans]
In-house databases/ resources
References
1
Obesity and Overweight Factsheet no 311. World Health Organisation. Updated March 2013
Accessed via http://www.who.int/mediacentre/factsheets/fs311/en/index.html on 06/03/2013
2 Chapter 4.5 Drugs used in the treatment of obesity Joint Formulary Committee. British National
Formulary. [February 2013] ed. London : British Medical Association and Royal Pharmaceutical
Society of Great Britain; [2013].
Available through NICE Evidence Search at www.evidence.nhs.uk
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Medicines Q&As
3
Vinson JA, Burnham BR and 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, Metabolic Syndrome, and Obesity: Targets and Therapy 2012: 5; 21-27
4 Green coffee monograph. In: Natural Medicines Comprehensive Database. Accessed via
http://naturaldatabase.therapeuticresearch.com/home.aspx?cs=&s=ND on 06/03/2013
5 The £14 diet pill that is the talk of Hollywood. Daily Mail, 27th February 2013. Accessed via
http://www.dailymail.co.uk/femail/article-2284789/The-14-diet-pill-talk-Tinseltown---Demi-Moore-KatyPerry-J-Lo-A-listers-rumoured-taking-green-coffee-tablets-stay-super-slim.html
6 Caffeine Monograph: In: Natural Medicines Comprehensive Database. Accessed via
http://naturaldatabase.therapeuticresearch.com/home.aspx?cs=&s=ND on 06/03/2013
7 Svetol Information. In: Natural Medicines Comprehensive Database. Accessed via
http://naturaldatabase.therapeuticresearch.com/home.aspx?cs=&s=ND on 06/03/2013
8 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 controlled trials. Gastroenterology Research and
practice. 2011; article ID 382852
9 Dellalibera O, Lemaire B, Lafay S. Svetol, green coffee extract, induces weight loss and increases
lean to fat mass ratio in volunteers with overweight problem. Phytotherapie 2006; 4(4): 194-197
Available through NICE Evidence Search at www.evidence.nhs.uk
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