The U.S. Pharmacopeia will require dietary supplements containing green tea extracts and black cohosh to carry cautionary statements about possible liver damage if those products are labeled as conforming to USP standards.
The announcement came in June after the USP Dietary Supplements Information Expert Committee reviewed numerous case reports suggesting a potential link between those herbals and liver damage. "The cautionary statements are designed to alert the public and health care practitioners of potential adverse effects to reduce the risks associated with ingesting dietary supplements," said Gabriel Giancaspro, USP director of dietary supplements, in a release.
The Federal Food, Drug and Cosmetic Act recognizes the USP-National Formulary publication as the official compendia for drugs marketed in the United States. However, in the case of dietary supplements, unless they carry the USP label, compliance is voluntary, Giancaspro said later via e-mail.
Daniel Fabricant, Natural Products Association vice president of scientific and regulatory affairs, said it seems the USP is being overly cautious and its reliance on case reports alone does not support current research. "There's no mechanistic data … where they can show a causative link," he said.
Black cohosh has a long history of use for rheumatism, and more recently, has become a popular supplement for menopause symptoms. Fabricant said randomized studies involving about 3,000 women and black cohosh have not shown any toxic effects on the liver.
Green tea and green tea extract have numerous perceived uses, including treating and preventing a variety of cancers, as well as increasing mental alertness. Giancaspro said the cautionary statement only affects green tea extracts because some extract preparations contain much higher concentrations of epigallocatechin gallate, which he said has shown hepatotoxicity at high doses or concentrations in several animal and in vitro studies.
The cautionary statement for green tea extracts, for example, includes a warning that it should be taken with a meal. "Bioavailability is reduced when taken with food, thus reducing the risks of hepatotoxicity," Giancaspro said.
Giancaspro said the committee "is unaware of significant safety issues" with the supplements as long as the warning label appears. "The committee believes that risks can be reduced by the presence of a cautionary statement," he explained.
Both cautionary statements say that in "rare cases" the supplements have been reported to affect the liver and recommend discontinuing their use if the user has a liver disorder or develops symptoms of liver trouble, such as abdominal pain, dark urine or jaundice.
"There really isn't risk with responsible use," Fabricant said.
The USP allows for a 60-day comment period from the time when the revisions appear in the USP's Pharmacopeial Forum, a journal the private nonprofit organization uses to develop and revise its standards through public discourse. No release date was initially reported for the green tea extract cautionary statement. The cautionary statement for black cohosh was scheduled to appear in September.
Natural Foods Merchandiser volume XXVIII/number 8/p. 11