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      • How well does Black cohosh work?
      • Is Black cohosh safe?
      • Black cohosh conclusions
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How well does Black cohosh work?

Biological mechanism

Black cohosh has been demonstrated to have organ-specific oestrogenic effects and were characterised as selective oestrogen-receptor modulators (ref 1). However, the most recent investigations do not support an oestrogen receptor-mediated mechanism of action for black cohosh (ref 2). The mechanism of action of black cohosh is still not well understood. Studies found that an ethanol extract of black cohosh did not stimulate growth of oestrogen- and progesterone-positive breast cancer cells in vitro (ref 15, 16). Administration of black cohosh has not changed serum FSH or LH levels or vaginal cytological findings (ref 13, 17-19).

Clinical studies

Two randomised-controlled trials in female breast cancer patients were identified for black cohosh (ref 13, 14); one of these was double-blind and placebo-controlled (ref 13). The characteristics and main findings are summarised below.

Both black cohosh and placebo groups reported a decline in the number and intensity of hot flushes (ref 13). However, the differences between groups were not statistically significant. Significant differences in improvement were observed only for sweating. Black cohosh intake did not alter follicle-stimulating hormone (FSH) or luteinizing hormone (LH) levels. The major limitations of this trial include the small sample size, the high dropout rate (18.8%), the short treatment period (two months), and the low dose of black cohosh (40 mg/day).

The other trial specifically examined the effectiveness of black cohosh for the relief of hot flushes in women with a history of breast cancer (ref 14). A 12-month treatment period of Cimicifuga racemosa combined with tamoxifen showed significantly better effects on the number and severity of hot flushes compared to tamoxifen (usual care) alone. Forty-two out of 90 patients (46.7%) in the herbal treatment group were free of hot flushes while no patient was without hot flushes in the tamoxifen group. Severe hot flushes were reported by 22 patients (24%) in the intervention group, and 34 (74%) in the tamoxifen group. However, this randomised trial has methodological weaknesses, such as being open-label, non-placebo-controlled and not blinded (ref 14).

Summary of randomised controlled trials

Study - Jacobson (ref 13)
Participants (n) - Patients diagnosed as breast cancer who completed primary therapy and experienced hot flushes (85)
Interventions - 1 tablet black cohosh or placebo (Remifemin®) twice daily for 60 days
Outcomes - Number and intensity of hot flushes, adverse event.
Main findings - Black cohosh was not significantly more efficacious than placebo against hot flushes and did not alter FSH or LH levels.

Study - Hernandez Munoz (ref 14)
Participants (n) - Premenopausal breast cancer survivors aged 35-52 years (136)
Interventions - CR BNO 1055 (Menofem®/Klimadynon®) for 12 months, plus tamoxifen 20 mg/day orally for 5 years; control group only tamoxifen 20 mg/day orally for 5 years.
Outcomes - Number and intensity of hot flushes, adverse event.
Main findings - The combination of CR BNO 1055 with tamoxifen for 12 months reduced the number and severity of hot flushes compared with tamoxifen alone.

References

1.Anonymous. Cimicifuga racemosa. Monograph. Alternative Medicine Review 2003; 8(2):186-9.

2.Mahady GB, Fabricant D, Chadwick LR, Dietz B. Black cohosh: an alternative therapy for menopause? Nutr Clin Care 2002;5(6):283-9

13.Jacobson JS, Troxel AB, Evans J, Klaus L, Vahdat L, Kinne D, et al. Randomised trial of black cohosh for the treatment of hot flushes among women with a history of breast cancer. J Clin Oncol 2001; 19(10):2739-45.

14.Hernandez Munoz G, Pluchino S. Cimicifuga racemosa for the treatment of hot flushes in women surviving breast cancer. Maturitas 2003; 44(Suppl 1):S59-65.

15.Wade C, Kronenberg F, Kelly A, Murphy PA. Hormone-modulating herbs: implications for women’s health. J Am Med Women’s Assoc. 1999; 54:181-3.

16.Zava DT, Dollbaum CM, Blen M. Estrogen and progestin bioactivity of foods, herbs, and spices. Proc Soc Exp Biol Med 1998; 217:369-78.

17.Liske E. Therapeutic efficacy and safety of Cimicifuga racemosa for gynecologic disorders. Adv Ther 1998; 15:45-53.

18.Pepping J. Black cohosh: Cimicifuga racemosa. Am J Health Syst Pharm 1999; 56:1400-2.

19.Lieberman S. A review of the effectiveness of Cimicifuga racemosa (black cohosh) for the symptoms of menopause. J Women’s Health 1998; 7:525-9.