Safety of Green Tea Extracts

Abstract

Green tea [Camellia sinensis (L.) Kuntze] is the fourth most commonly used dietary supplement in the US. Recently, regulatory agencies in France and Spain suspended market authorization of a weight-loss product containing green tea extract because of hepatotoxicity concerns. This was followed by publication of adverse event case reports involving green tea products. In response, the US Pharmacopeia (USP) Dietary Supplement Information Expert Committee (DSI EC) systematically reviewed the safety information for green tea products in order to re-evaluate the current safety class to which these products are assigned. DSI EC searched PubMed (January 1966-June 2007) and EMBASE (January 1988-June 2007) for clinical case reports and animal pharmacological or toxicological information. Reports were also obtained from a diverse range of other sources, including published reviews, the US FDA MedWatch programme, USP's MEDMARX adverse event reporting system, the Australian Therapeutic Goods Administration, the UK Medicines and Healthcare products Regulatory Agency, and Health Canada's Canadian Adverse Drug Reaction Monitoring Program. Case reports pertaining to liver damage were evaluated according to the Naranjo causality algorithm scale. In addition, the Committee analysed information concerning historical use, regulatory status, and current extent of use of green tea products. A total of 216 case reports on green tea products were analysed, including 34 reports concerning liver damage. Twenty-seven reports pertaining to liver damage were categorized as possible causality and seven as probable causality. Clinical pharmacokinetic and animal toxicological information indicated that consumption of green tea concentrated extracts on an empty stomach is more likely to lead to adverse effects than consumption in the fed state. Based on this safety review, the DSI EC determined that when dietary supplement products containing green tea extracts are used and formulated appropriately the Committee is unaware of significant safety issues that would prohibit monograph development, provided a caution statement is included in the labelling section. Following this decision, USP's DSI ECs may develop monographs for green tea extracts, and USP may offer its verification programmes related to that dietary ingredient.

Dietary Supplements for Improving Body Composition and Reducing Body Weight: Where Is the Evidence?

“…GT extracts have been associated with liver damage, especially if ingested on an empty stomach (Sarma et al, 2008).…”

“…However, the green tea catechin group lost significantly more abdominal body fat, both total and subcutaneous, and had lower fasting serum triglycerides than the control group. Sarma et al (2008) systematically reviewed the safety of green tea extracts. Of the 216 green tea case reports they examined, 34 were related to liver damage, with 27 categorized as possible causality.…”

Hypoglycemic Property of Ginger and Green Tea and their Possible Mechanisms in Diabetes Mellitus

“…Another study reported that side effects of green tea had increased when taken on an empty stomach, and high doses may cause liver toxicity. Recently, regulatory agencies in France and Spain suspended market authorization of a weight loss product containing green tea extract because of the hepatotoxicity concerns [60].…”

Complementary and alternative medications in hepatitis C infection

“…An example of this is Exolise (Arkopharma, France), a weight loss supplement containing high EGCG levels that was withdrawn from the market in April 2003 due to 13 cases of attributable liver injury [35] . Between 1966 and 2008, 216 case reports of toxicity with green tea extracts were identified by the United States Pharmacopeia, of which 34 were concerning for liver toxicity [36] . Recent animal studies with high doses of GTE and EGCG have described dose-dependent hepatotoxicity resulting in severe morbidity and mortality [37] .…”