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Black Cohosh Supplementation May Help To Prevent Breast Cancer Risk

 James Meschino DC, MS, ROHP

Epidemiological studies and some experimental evidence suggest that soy isoflavones, which act as phytoestrogens (plant-based estrogens) in the body, help reduce risk of breast cancer. In Europe the herb known as black cohosh, which also contains phytoestrogen compounds, has been used with great success for the past 40 years as a treatment for menopausal symptoms, PMS and other female reproductive disorders (i.e., dysmenorrhea). Black cohosh has been shown to be very nontoxic with few reported adverse side effects, primarily involving mild nausea. As such, many European physicians prescribe it instead of hormone replacement therapy for postmenopausal women, and as a treatment for a variety of female complaints. It has a safety profile that is superior to hormone replacement, in that hormone replacement therapy is known to increase the risk of breast cancer by 2.3% per year and increases risk of other conditions as well.

Intrigued by the physiological effects of black cohosh and its phytoestrogen agents, a number of researchers have recently set out to examine the impact of black cohosh on various human breast cancer cell lines. The assumption by many investigators was that black cohosh would encourage the growth of breast cancer cells because it has a weak estrogenic effect, which is likely to promote proliferation of these cells; however, these studies have demonstrated the opposite effect. In these studies black cohosh has been shown to have an anti-proliferative effect on a number of human breast cancer cell lines. Essentially, black cohosh extract prevents breast cancer cells from dividing in all the in vitro studies performed to date. In one study, black cohosh was shown to increase the effectiveness of the breast cancer drug Tamoxifen, when both were used concurrently. In the study by Foster, the authors concluded that extracts of black cohosh can be taken safely by patients who are susceptible to breast cancer (and possibly should be used as a means of chemoprevention). In reference to these studies, D. Dixon-Shanes and N. Shaikh remark in the journal Oncology Report, (Nov-Dec, 1999), that herbs such as black cohosh and soy isoflavones show potential as natural agents that may reduce the risk of breast cancer (if taken prophylactically). As one in nine women in the U.S. develops this disease, it may be prudent for North American women to use a well-designed black-cohosh and soy isoflavone-containing supplement as a preventive measure throughout adult life (unless contraindications are present), to discourage the promotion of breast cancer should a breast cancer cell arise. Theoretically, this would give the immune system a better chance to destroy the cancer cell before it has an opportunity to thrive; at least this is the current thinking.

The standardized grade that demonstrates clinical efficacy involves the use of black cohosh extract providing 2.5% triterpene content. A usual daily dosage for menopause is 40 or 80 mg, twice per day. Half this dosage may be prudent simply to support reproductive health throughout the premenopausal years and as a primary intervention to potentially aid in risk reduction of breast cancer. Further studies are planned to enhance our understanding of this important and timely subject.


  1. Black Cohosh: Safe for Menopause. Herb Quarterly; Dec. 21, 1999; N.84: pp 7-8 Long Mountain Press, Inc.
  2. Dixon-Shanies, D., Shaikh, N. Growth inhibition of human breast cancer cells by herbs and phytoestrogens. Oncol Rep, 1999 Nov-Dec; vol. 6 (6), pp. 1383-7
  3. Ainsworth, C. The holistic herbal approach to primary dysmenorrhea (painful periods). Canadian Journal of Herbalism 2001; 22 (1): pp 2-9, 38-40
  4. Black cohosh for hot flashes? Consumer Reports on Health, Oct 2001, Vol. 13 Issue 10: p 6
  5. McKenna, Dennis J.; Jones, Kenneth; Humphrey, Sheila; Hughes, Kerry. Black cohosh: Efficacy, Safety, and Use in Clinical and PreClinical Applications. Alternative Therapies in Health & Medicine; May 5, 2001; V.7, N.3: pp 93-100


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