A review of black cohosh, said to be the most comprehensive to date, finds it to be safe, just days after another study suggested that the herb, taken as an alternative to hormone replacement therapy (HRT), could trigger the spread of breast cancer.
The report in the current issue of Menopause, the bimonthly journal of the North American Menopause Society, evaluated pre-clinical and clinical research in oestrogen-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 a recent abstract presented this week at the American Association for Cancer Research (AACR), which found black cohosh to speed up the spread of breast tumours in mice.
"This paper should reassure health professionals that they can safely recommend black cohosh to their menopausal patients who cannot or choose not to take HRT," said lead author Dr Tieraona Low Dog, Clinical Assistant Professor at the University of New Mexico Department of Family and Community Medicine and advisor to the NIH Center for Complementary and Alternative Medicine. "Well studied, non-oestrogenic symptom management alternatives help address individual women's symptoms, health profile and personal preferences."
The paper, entitled '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as well as the FDA and World Health Organisation adverse event reporting systems, monographs, compendia, internal unpublished data from a major manufacturer, foreign literature, and historical, anecdotal reports.
In human clinical trials, uncontrolled reports, and post-launch evaluations of over 2800 patients, the review found a low incidence of adverse events with black cohosh - 5.4 per cent. Of the reported adverse events, 97 per cent were minor and did not result in discontinuation of therapy, and the only severe events were not attributed to Cimicifuga treatment, according to the report.
"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 oestrogen therapy is contraindicated," concluded the authors.
Many other black cohosh products use different extracts, (not isopropanolic preparations) which have not been as well studied.