Q & A Library

Originally published 12/31/2007

Actually, it was not the FDA, but the U.S. Pharmacopeia (USP) that in June 2007 proposed requiring a cautionary statement (not a warning label) on black cohosh (an herb that may relieve hot flashes and other symptoms of menopause) and on all dietary supplements containing green tea extracts. The USP is the official public standards-setting authority for all drugs (both prescription and over-the-counter) dietary supplements, and other healthcare products manufactured and sold in the United States. USP standards are recognized and used in more than 130 countries.

My colleague Tieraona Low Dog, M.D., director of education at the Program on Integrative Medicine, who sits on the USP committee that proposed the cautionary statements, tells me that the action was taken after a thorough review of all the reports to the FDA of adverse events for both black cohosh and green tea extracts, including liver damage. If there is a relationship between green tea extracts and liver damage, Dr. Low Dog said that the incidence appears to be exceedingly low. Still, the committee decided that consumers should be aware of the growing number of reports suggesting that concentrated green tea extracts (predominantly those prepared with alcohol), with and without other ingredients, may cause elevation of liver enzymes and liver damage.

As far as black cohosh is concerned, Dr. Low Dog tells me that a number of countries including Australia, Canada, Sweden and the United Kingdom now require cautionary statements on black cohosh products based upon reports of liver damage (34 so far) and liver failure. In a few cases, the damage was so severe that liver transplants were necessary. Here, too, the committee agreed that consumers should be alerted to this rare but possible risk.

The proposed cautionary statement for supplements containing green tea extracts states that they must be taken before a meal and notes that in rare cases these supplements have been reported to adversely affect the liver. The proposed wording for the cautionary statement on black cohosh products does not mention taking it with meals and omits the word "adversely" before noting reports that it can affect the liver. Both statements advise consumers to discontinue use of the supplements if they develop symptoms indicating liver dysfunction, such as nausea and vomiting, abdominal pain, or dark urine. Anyone who already has liver disease should be cautious about using these products.

For the record, I have always recommended the best way to get the health benefits of green tea is to drink the tea itself, which poses no risk, and I have never seen anyone on black cohosh develop liver problems. The American Botanical Council, citing an NIH sponsored panel, believes that there was not enough evidence of a relationship between black cohosh and liver toxicity to justify a consumer warning, and other groups are responding to the USP recommendation. I am following these developments closely.

Andrew Weil, M.D.