Black cohosh, soy, and other naturopathic products failed to relieve menopausal symptoms in a large, yearlong, double-blind trial.

A research team from several medical centers in the Seattle area recruited 351 volunteer peri- or postmenopausal women (aged 45-55) and randomly assigned them to one of five groups: placebo; black cohosh (160 mg/day); estrogen (0.625 mg/day); a “multibotanical” that combined black cohosh, alfalfa, boron, chaste tree, dong quai, false unicorn, licorice, oats, pomegranate, and ginseng; and a multibotanical plus a soy diet.

At the end of the yearlong study period, there were no statistically significant differences in the incidence or intensity of hot flushes or night sweats per day among any of the herbal-treatment groups and the placebo group. In fact, the group taking the multibotanical plus soy reported more symptoms relative to the placebo group.

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The women taking estrogen were the only patients to report meaningful improvement vs. placebo; the number of their vasomotor symptoms declined by half.

Black cohosh, a forest-loving plant that produces long clusters of white blossoms, is widely promoted in health-food stores and on the Internet as a phytoestrogenic compound that relieves menopausal symptoms. There have been a number of studies of the treatment, but most have been inconclusive and weakly designed, lacking placebo controls. The new trial, partly funded by NIH’s Center for Complementary and Alternative Medicine, is by far the largest and most rigorous on record.

“Regrettably,” the Seattle researchers concluded, “this trial and the totality of evidence indicate that black cohosh used in isolation or in a multibotanical product has little potential to play an important role in relief of vasomotor symptoms” (Ann Intern Med. 2006;145:869-879).