Black cohosh is promoted as an alternative to estrogen-based hormone replacement therapies for treating menopausal symptoms including hot flashes. It may also be useful for hot flashes due to breast cancer treatments, but more research is needed before it can be recommended or advised against for this use, according to the Memorial Sloan-Kettering Cancer Center in New York. The question of whether this supplement has estrogenic effects also merits more study. Consult a doctor before trying this supplement, and use it under a doctor's supervision -- especially if you have a hormone-sensitive condition.
Estrogenic Effects
Not much is known about black cohosh's possible estrogenic or anti-estrogenic effects, despite its widespread use for menopausal complaints, notes O. Zierau, lead author for a 2002 study published in "The Journal of Steroid Biochemistry and Molecular Biology." Part of the problem is conflicting scientific data. Zierau's study concludes that black cohosh has compounds with antiestrogenic properties. Newer data dispute the long-held theory that black cohosh is estrogenic, agrees G.B. Mahady, author of a 2003 review published in "Nutrition Reviews." Former theories were that compounds in black cohosh bind to estrogen receptors, up-regulate estrogen-dependent genes and possibly stimulate estrogen-dependent tumors. As of 2011, controversy on black cohosh's possible estrogenic effects remains, notes MSCC. In general, herbs with estrogenic effects are not advised for people who have hormone-sensitive conditions like breast cancer.
Mestastis Risk
Black cohosh may increase your risk for breast cancer metastasis, note George T. Grossberg and Barry Fox, authors of "The Essential Herb-Drug-Vitamin Interaction Guide." A 2008 study published in "Cancer Research" concludes that black cohosh supplementation significantly increases tumor mestasis. Metastatic progression is linked your likelihood of survival. However, it appears the supplement does not influence your breast cancer risk if it's taken prior to the time tumors are formed, notes lead study author V.L. Davis. Since this study was done on mice, more research is needed to correlate the study's findings to women who are taking black cohosh products at various stages of breast cancer development, Davis notes. The results also point to the need for caution among women who take black cohosh -- especially when you take this supplement for extended time frames, Davis says.
Tamoxifen Symptom Relief
Breast cancer patients who are being treated with the antiestrogen tamoxifen often find that it induces or aggravates menopausal complaints. Taking black cohosh at the same time can alleviate many of these, including anxiety, hot flashes, sleep problems and sweating, according to a 2011 observational study of 50 breast cancer patients published in "Gynecological Endocrinology." This leads lead study author M. Rostock to the conclusion that black cohosh is a reasonable aid for women suffering breast cancer who are treated with tamoxifen. However, other studies have concluded that black cohosh is no more effective than a placebo, according to University of Maryland Medical Center. The herb also may interfere with cancer therapy drugs or radiation, both common breast cancer treatments, reports UMMC.
Expert Insight
The bottom line is that the effect of black cohosh on breast cancer is not well studied and conflicting information on its possible effects exists, according to MSCC. On top of this, the efficacy and safety of black cohosh beyond six months of use have not been proven. Also, any influence that black cohosh may have on anti-estrogen drugs such as tamoxifen or hormone replacement therapy remains unclear as of 2011, according to MayoClinic.com. Before using black cohosh you should know that it is associated with cases of liver damage. What all this means, note the experts at MSCC, is that you need to use black cohosh under the supervision of a physician -- especially if you have a history of breast cancer or have risk factors for breast cancer.
References
- Memorial Sloan-Kettering Cancer Center: Black Cohosh
- "The Journal of Steroid Biochemistry and Molecular Biology"; Antiestrogenic Activities of Cimicifuga racemosa Extracts; O. Zierau, et al.; 2002
- "Nutrition Reviews": Is Black Cohosh Estrogenic?; G.B. Mahady; 2003
- "The Essential Herb-Drug-Vitamin Interaction Guide" George T. Grossberg and Barry Fox; 2007
- "Cancer Research"; Black Cohosh Increases Metastatic Mammary Cancer in Transgenic Mice Expressing c-erbB2; V.L. Davis, et al.; 2008
- "Gynecological Endocrinology"; Black Cohosh (Cimicifuga racemosa) in Tamoxifen-Treated Breast Cancer Patients with Climacteric Complaints - A Prospective Observational Study; M. Rostock, et al.; 2011
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