The CSPI also called on the National Institutes of Health, currently studying the effectiveness of black cohosh on women, to advise study subjects of the possible risks and to be on alert for any adverse effects.
"Women, particularly women who have had breast cancer, should think twice before taking black cohosh," said CSPI senior nutritionist David Schardt.
As women turn increasingly to natural alternatives and away from the adverse side effects of hormone replacement therapy (HRT), herbs such as black cohosh have gained in popularity.
In a letter this week to FDA Commissioner Mark McClellan, CSPI said that the FDA should also notify physicians about the potential risks of black cohosh, and urge them to submit any data on liver toxicity or cancer metastasis from patients taking black cohosh.
"Women taking black cohosh should be monitored for evidence of liver problems," said Stanley M. Cohen, a physician at Rush Medical Center in Chicago. "If physicians look for this, we'll be seeing more cases."
Fuelled by question marks over black cohosh, a raft of recent studies have investigated the safety of the herb. A review last year of black cohosh, said to be the most comprehensive to date, found it to be safe, just days after another study suggested that the herb could trigger the spread of breast cancer.
The paper, 'Critical Evaluation of the Safety of Cimicifuga Racemosa in Menopause Symptom Relief', is the first to review all published literature pertaining to pre-clinical and clinical safety of various forms of Cimicifuga (black cohosh), as well as the FDA and World Health Organization adverse event reporting systems, monographs, compendia, internal unpublished data from a major manufacturer, foreign literature, and historical, anecdotal reports.
Published in the July/August issue of Menopause, the bimonthly journal of the North American Menopause Society, it evaluated pre-clinical and clinical research in estrogen-sensitive populations, including women at risk for breast cancer and breast cancer survivors, as well as human cell lines most relevant to breast cancer.
It found strong evidence for the safety of several black cohosh extracts in humans, contrasting with an abstract presented in July at the American Association for Cancer Research (AACR), which found black cohosh accelerated the spread of breast tumors in mice.
"Although the effects of Cimicifuga may be dependent on the specific extract preparation, this review clearly supports the safety of specific Cimicifuga extracts, particularly isopropanolic preparations, for use in women experiencing menopausal symptoms and as a safe alternative for women in whom estrogen therapy is contraindicated," concluded the authors.