Published: August 2009
Prescriber Update 30(3): 21
Green Tea (Camellia sinensis) is a widely used dietary supplement and is often promoted for weight loss.
Recently the United States Pharmacopoeia (USP) published a review of the safety of Green Tea extracts.1 A total of 216 case reports of suspected adverse reactions were reviewed; 34 reports concerned liver damage.
In 2003 French and Spanish authorities suspended market authorisation of Exolise, a weight loss product containing green tea extract. There had been 13 reports of elevated liver enzymes with an onset time of 9 days to 5 months. Twelve patients recovered after stopping Exolise and one patient, with regular alcohol intake, progressed to liver failure.
More recently the food supplement Hydroxycut, of which some formulations contain Green Tea extract, was removed from sale in New Zealand, Canada and the United States. This action was due to concerns over liver toxicity, seizures, cardiovascular disorders and muscle damage.
In the review conducted by the USP, clinical pharmacokinetic and animal toxicological information indicated that consumption of Green Tea extracts on an empty stomach increased the risk of liver related adverse effects. The USP recommends that complementary medicines containing green tea should only be taken with food.
Prescribers are reminded to ask about the use of complementary medicines and food supplements in patients with elevated liver enzymes and report any suspected adverse reactions to complementary medicines to CARM.