Medicines Q&As
Q&A 418.1
What are the safety concerns surrounding use of green coffee
extract for weight loss?
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: 8th April 2013
Background
Green coffee refers to coffee beans that haven’t yet been roasted. Green coffee extract (GCE) has
become popular as an herbal weight loss aid following some recent media attention and celebrity
endorsements1. Information on the evidence of effectiveness for green coffee extract is available in
Medicines Q&A 417 “What is the evidence that green coffee extract works to reduce weight?”
Whilst various online retailers are selling GCE as a natural, safe supplement, there is a limited
amount of information available regarding the safety of these preparations.
Answer
Products which are not licensed or regulated by the Medicines and Healthcare Products
Regulatory Agency’s Traditional Herbal Registration (THR) scheme should not be
recommended as the safety and quality of the product cannot be guaranteed2. At time of writing,
there are no GCE products which hold THR status in the UK3.
As there is a general lack of information on the safety of herbal products, lack of a documented safety
issue or drug interaction may not mean one does not exist, but merely that it has not been
investigated or reported in the medical literature yet.
Long Term Safety
Trials involving GCE have been limited in length, with the longest being of 12 weeks duration. Safety
of GCE beyond this time has not been assessed1,4.
Adverse effects
Overall, it would appear that GCE is well tolerated. As yet, no significant adverse effects have been
reported in clinical trials, although these have been limited in number and size 1,4. Adverse reactions
appear to be mainly due to the caffeine content of some preparations, although decaffeinated
preparations are available1,5. Decaffeinated products should theoretically produce less adverse
effects, although the unregulated nature of these products, along with the lack of information about
their use, cannot guarantee their safety.
Serious adverse effects of caffeine are usually associated with excessive doses and include
palpitations, anaphylaxis, and metabolic acidosis 6,7.
Common adverse reactions include gastrointestinal upset, headache, insomnia, agitation,
restlessness, and nervousness. The presence of a clinically significant caffeine withdrawal syndrome
remains controversial, but may result in headache, tiredness, decreased energy and attentiveness,
and depressed mood1,6.
Little is known about the potential adverse effect profile of chlorogenic acid. Some studies suggest
that, contrary to earlier beliefs, pure chlorogenic acid does not produce allergic reactions, but
contaminants found in some lower purity extracts may be able to provoke anaphylaxis or
allergies8,9,10. One study performed in dogs appeared to suggest that Chinese herbal injections
containing chlorogenic acid could lead to significant changes in both the liver and kidneys 10. The
clinical relevance of these changes in humans remains unknown.
Available through NICE Evidence Search at www.evidence.nhs.uk
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Medicines Q&As
Short term (1 week treatment period, n=20), high dose intake of chlorogenic acid was found in one
placebo controlled, crossover study to be associated with increased levels of homocysteine. High
homocysteine levels are considered to be a risk factor for cardiovascular disease. However, whether
such increases are sustained following more long term use remains unknown, and the amounts of
chlorogenic acid consumed by the subjects (2 grams) are much higher than those which would be
consumed in the average green coffee extract product11.
Any adverse effects experienced whilst taking green coffee extract should be reported via the
MHRA’s Yellow Card Scheme.
Cautions
Green coffee extract should be used with caution or avoided in the following groups of people or
disease states:
Anxiety disorders
Bleeding disorders
The caffeine content of GCE can worsen anxiety states.
Caffeine may have antiplatelet activity, and can prolong bleeding time.
Although this has not been documented to worsen bleeding conditions in
humans, the use of GCE in patients with bleeding disorders should be
done cautiously.
Diabetes
There is a possibility that caffeine can worsen insulin resistance and
cause an increase in hypoglycaemia frequency. It can enhance the
warning signs of a hypoglycaemic attack. This effect has not been wellstudied, so the likelihood of any clinically significant effects remains
unknown.
Gastro-intestinal
Because caffeine can cause diarrhoea, it may exacerbate existing
Disorders
diarrhoea or worsen conditions like Irritable Bowel Syndrome.
Glaucoma
Caffeine leads to an increase in intra-ocular pressure, which may be
problematic in patients with glaucoma.
Hypertension
There is limited evidence to suggest that a decaffeinated GCE may
reduce blood pressure. However, products containing caffeine may lead to
an increase in blood pressure, particularly in people who are not habitual
coffee drinkers.
Osteoporosis
Caffeine may increase loss of calcium in the urine. However available
evidence is inconclusive. In the UK, there are no specific
recommendations for limiting caffeine intake, but the modest likelihood of
an effect should be borne in mind if a green coffee product is being
considered.
Pregnancy and
There is not enough information on the use of GCE in pregnancy or
lactation.
breast-feeding to assess its safety: It should therefore be avoided in
pregnant or breast-feeding women.
Weight loss during pregnancy may be harmful and should be discouraged
unless under medical supervision.
Renal or Liver disease
Limited laboratory studies appear to suggest that chlorogenic acid can
cause liver or kidney changes. Until more is known, it would be prudent to
avoid GCE in patients with pre-existing liver or kidney disease.
Various laboratory tests Caffeine can affect the results of various types of laboratory tests, for
example theophylline levels, pulmonary function tests and blood glucose
levels amongst others
Table 1: Cautions and contra-indications of GCE products1,6,10,12,13
Interactions
Interaction
Alcohol
Severity
Mild
Likelihood
Probable
Management
Be cautious
about using
both together
Evidence
Theoretical
Bisphosphonates
Moderate
Probable
Separate
Theoretical
Notes
Alcohol may increase
caffeine levels, leading
to a higher likelihood of
adverse reactions.
Caffeine significantly
Available through NICE Evidence Search at www.evidence.nhs.uk
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administration
by at least two
hours
Be cautious
about using
both together
Avoid large
amounts of
caffeine
reduces the absorption
of bisphosphonates
Anticoagulants/
Antiplatelets
Moderate
Unlikely
Theophylline
Mild
Probable
Clozapine
Moderate
Possible
Be cautious
about using
both together
Theoretical
Antidepressants
Mild-High
Probable
Be cautious
about using
both together.
Avoid excessive
doses of
caffeine with
MAOIs
Theoretical
Be cautious
Theoretical
Disulfiram
Decongestants/
Mild
High
Probable
Probable
stimulants
Lithium
Moderate
Probable
Theoretical
Caffeine might
increase bleeding risk
Theoretical
Theophylline levels
may be increased by
the caffeine in green
coffee products.
Caffeine might
exacerbate psychotic
symptoms, as well as
increasing clozapine
levels, leading to a
greater risk of adverse
effects
Caffeine levels may be
increased by SSRI
antidepressants.
A serious hypertensive
crisis may occur if
large doses are taken
alongside MAOI
antidepressants.
Disulfiram may
about using
increase caffeine
both together
levels.
Be cautious
Theoretical
Additive actions can
about using
lead to increased risk
both together
of side effects.
Be cautious
Case
Abruptly stopping
about using
reports
green coffee extract
both together
may affect lithium
levels. Lithium tremor
may be worsened.
Quinolones e.g.
Mild
Probable
ciprofloxacin
Be cautious
Theoretical
Quinolone antibiotics
about using
may increase caffeine
both together
levels, leading to
increased risk of side
effects.
Blood pressure
Mild-
lowering drugs
Moderate
Possible
Be cautious
Theoretical
Some blood pressure
about using
lowering medicines
both together
e.g. verapamil may
increase levels of
green coffee, leading
to increased side
effects risk.
Available through NICE Evidence Search at www.evidence.nhs.uk
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Medicines Q&As
Table 2: list of possible interactions of GCE. Please note that this list is not exhaustive and lack of a
listed interaction may not mean that one does not exist 1,6,14.
Summary
There is a limited amount of information available regarding the safety of green coffee extract for
weight loss. It appears to have been well-tolerated in studies but more information is required before
claims of its safety can be considered conclusive.
Certain groups of people, including those who are pregnant or breast-feeding, or who have bleeding
disorders, diabetes, or osteoporosis should use GCE cautiously or avoid its use where possible.
GCE has the potential to interact with a number of medicines and lab tests.
Limitations
Information on the safety of GCE is limited. This Medicines Q&A is therefore not an exhaustive list of
every potential safety problem. Many of the issues mentioned in this Q&A are theoretical in nature
due to the lack of published evidence.
Quality Assurance
Prepared by
Hayley Johnson, Regional Drug & Therapeutics Centre, Newcastle upon Tyne
Date Prepared
8th April 2013
Checked by
Hayley Sharpe, Regional Drug & Therapeutics Centre, Newcastle upon Tyne
Date of check
17th April 2013
Search strategy
AMED: (green AND coffee).af;
Embase (green AND coffee).af AND SAFETY/
CHLOROGENIC ACID/ae, it, to [ae=Adverse Drug Reaction, it=Drug Interaction, to=Drug
Toxicity]
Medline (green AND coffee).af AND SAFETY/
In-house database/ resources
References
1
Green Coffee monograph. Natural Medicines Comprehensive Database. Accessed via
http://naturaldatabase.therapeuticresearch.com/nd/Search.aspx?cs=&s=ND&pt=100&id=1264&ds=&n
ame=Green+Coffee+Extract+%28GREEN+COFFEE%29&searchid=40518685 on 8th April 2013.
2 MHRA. Traditional Herbal Registration Certification Mark. Accessed via
http://www.mhra.gov.uk/Safetyinformation/Generalsafetyinformationandadvice/Herbalmedicines/TheT
HRscheme/index.htm on 8th April 2013
3 MHRA. List of products granted a Traditional Herbal Registration (THR). Accessed via
http://www.mhra.gov.uk/Howweregulate/Medicines/Herbalmedicinesregulation/RegisteredTraditionalH
erbalMedicines/LIstofproductsgrantedaTraditionalHerbalRegistrationTHR/index.htm on 8th April 2013
Available through NICE Evidence Search at www.evidence.nhs.uk
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Medicines Q&As
4
Onakpoya I, Terry R, and Ernst E. The use of green coffee extract as a weight loss supplement: a
systematic review and meta-analysis of randomised clinical trials. Gastroenterology Research and
Practice. 2011: Article ID 382852 doi: 10.1155/2011/382852
5 Svetol Information. In: Natural Medicines Comprehensive Database. Accessed via
http://naturaldatabase.therapeuticresearch.com/home.aspx?cs=&s=ND on 06/03/2013
6 Caffeine monograph. Natural Medicines Comprehensive Database. Accessed via
http://naturaldatabase.therapeuticresearch.com/nd/Search.aspx?cs=&s=ND&pt=100&id=979&ds=&na
me=CAFFEINE&searchid=40518685 on 8th April 2013
7 DRUGDEX®System: Caffeine (DrugPoints® Summary). In: Klasco RK (Ed): DRUGDEX® System
(electronic version). Truven Health Analytics Micromedex, Greenwood Village, Colorado, USA.
Available at: http://www.micromedexsolutions.com (cited: 8th April 2013).
8 Wang Z, Wang D, Yu Y et al. Study on allergenicity of chlorogenic acid in Qingkailing injection.
Zhongguo Zhongyao Zazhi, 2011. 36(14); 1870-1873.
9 Wu X, Yang H, Lin D et al. Comprehensive research and evaluation of chlorogenic acid allergy.
Zhongguo Zhongyao Zazhi 2010: 35(24): 3357-3361.
10 Li B, Dong X, Yang G-Q et al. Role of chlorogenic acid in the toxicity induced by Chinese herbal
injections. Drug and Chemical Toxicology. 2010; 33(4): 415-420.
11 Olthof M, Hollman P, Zock P et al. Consumption of high doses of chlorogenic acid, present in coffee
or of black tea increases plasma total homocysteine concentrations in humans. American Journal of
Clinical Nutrition 2001; 73: 532-538.
12 Scottish Intercollegiate Guidelines Network. Management of Osteoporosis Guidelines
http://www.sign.ac.uk/guidelines/fulltext/71/section4.html
13 Obesity in pregnancy monograph. UK Teratology Information Service v1. 2011.
14 Coffee Monograph. In: Williamson E, Driver S, Baxter K. Stockley’s Herbal Medicines Interactions.
[online] London: Pharmaceutical Press http://www.medicinescomplete.com [Accessed on 04 Mar
2013]
Available through NICE Evidence Search at www.evidence.nhs.uk
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