Nutrition Research News
Black Cohosh May Help Reduce Breast Cancer Risk
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.
The herb black cohosh, which contains phytoestrogen compounds, has been used in Europe with great success for 40 years as a treatment for menopausal symptoms, PMS and other female reproductive disorders (i.e., dysmenorrhea).
Black cohosh has been shown to be nontoxic, with few reported adverse side effects, primarily 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 superior to hormone replacement. Hormone replacement therapy is known to increase the risk of breast cancer (by 2.3 percent per year) and other conditions.
Intrigued by the physiological effects of black cohosh and its phytoestrogen agents, a number of researchers have recently set out to examine its impact 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 its weak estrogenic effect was likely to promote proliferation of these cells.
However, studies have demonstrated the opposite: Black cohosh has been shown to have an anti-proliferative effect on a number of human breast cancer cell lines. Essentially, black cohosh extract has prevented breast cancer cells from dividing in all of the in vitro studies reported 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).
As one in nine women in the U.S. develops this disease, it may be prudent for North American women to take a supplement containing black cohosh and soy isoflavones throughout adult life (unless contraindications are present) to discourage the promotion of breast cancer.
If black cohosh and soy isoflavones can inhibit the proliferation of breast cancer cells, then in theory, this would give the immune system a better chance to destroy cancer cells before they have an opportunity to thrive.
The standardized grade of black cohosh extract that demonstrated clinical efficacy provided 2.5 percent 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 underway to enhance our understanding of this important and timely subject.
Black cohosh: Safe for menopause. Herb Quarterly Dec. 21, 1999;84:7-8. Long Mountain Press, Inc.
Dixon-Shanies D, Shaikh N. Growth inhibition of human breast cancer cells by herbs and phytoestrogens. Oncol Rep 1999 Nov-Dec;6(6):1383-7.
Ainsworth C. The holistic herbal approach to primary dysmenorrhea (painful periods). Canadian Journal of Herbalism 2001;22(1):2-9,38-40.
Black cohosh for hot flashes? Consumer Reports on Health Oct 2001;13(10):6.
McKenna DJ, Jones K, Humphrey S, Hughes K. Black cohosh: Efficacy, safety, and use in clinical and preclinical Applications. Alternative Therapies in Health & Medicine May 5, 2001;7(3):93-100.
1/02/07 From an email:
" Freddi Kronenberg found it doesn't (black cohosh does not contain phytoestrogens). The assumption that it contained formononetin was from back in the early 80's but no one else ever found any so now everyone is saying it doesn't. It's no longer a true statement.
" . .The standardized grade of black cohosh extract that demonstrated clinical efficacy provided 2.5 percent triterpene content. A usual daily dosage for menopause is 40 or 80 mg, twice per day."
In 1998 Remifemin changed its dose from 40 mg twice a day to 20 mg twice a day.
Thanks for all your good work".
AACR abstract, 4/03
Cancer Invest, 2004
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