No Reduction in Menopause Symptoms With Black Cohosh or Red Clover
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In a randomized, double-blind, placebo-controlled trial that included 89 women, neither black cohosh nor red clover proved to be any more effective than placebo in relieving menopausal vasomotor symptoms.
Women were eligible for the 12-month trial if they experienced at least 35 vasomotor symptoms (hot flashes and night sweats) per week. Participants were assigned to one of four treatment arms:
• An ethanolic extract of below-ground parts of black cohosh (128 mg/day standardized to 7.27 mg triterpene glycosides).
• An ethanolic extract of the aerial parts of red clover (398 mg/day standardized to 120 mg isoflavones).
• Hormone therapy with 0.625 mg conjugated equine estrogens plus 2.5 mg medroxyprogesterone acetate.
• Placebo.
The primary endpoint was determination of the efficacy of black cohosh and red clover for the relief of vasomotor symptoms as compared with placebo; it was measured as the reduction of all vasomotor symptoms, reduction of hot flashes alone, and intensity of hot flashes as compared with placebo. Secondary outcomes included an evaluation of the safety of the botanical treatments.
The average number of vasomotor symptoms per week decreased over time in all study arms, as follows: black cohosh, 34% reduction; red clover, 57% reduction; placebo, 63% reduction; and hormone therapy, 94% reduction. None of the primary measures—number of vasomotor symptoms, number of hot flashes alone, or intensity of hot flashes—were reduced significantly in the black cohosh or red clover groups compared with the placebo group at any time point (3, 6, 9, or 12 months).
Of note, there also were no significant differences between the botanical treatments and placebo for any of the safety parameters, including breast and endometrial safety, liver enzymes, complete blood count, and lipid profiles. The authors concluded that “these positive safety outcomes are important because women may be expected to continue to use black cohosh and red clover, regardless of scientific clinical findings.”
Menopause. 2009;16(6):1156-66.