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USP Investigates Safety Of Green Tea Extracts

Green tea is the fourth most commonly used dietary supplement in the
United States. After the publication of adverse event case reports
involving green tea products and potential liver toxicity, the US
Pharmacopeia reviewed safety information for green tea products. 216
case reports on green tea products were analyzed including 34 reports
concerning liver damage. 27 reports pertaining to liver damage were
categorized as possible causality and seven as probable causality.
Pharmacokinetic and animal toxicological studies indicate 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. USP concluded “when dietary supplement products containing
green tea extracts are used in formulated appropriately the Committee
is unaware of significant safety issues that would prohibit monograph
development, provided that caution statement is included in the
labeling section.”

Safety of Green Tea Extracts : A Systematic Review by the US Pharmacopeia.
Drug Saf. 2008;31(6):469-84.. Sarma DN, Barrett ML, Chavez ML, Gardiner
P, Ko R, Mahady GB, Marles RJ, Pellicore LS, Giancaspro GI, Low Dog T.

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((R))
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.

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