Putting the kibosh on black cohosh.

The herbal supplement black cohosh, taken for relief of menopausal hot flashes, doesn't work any better than a placebo, a study finds.

Previous research had brought mixed results. Nevertheless, sales of black cohosh have soared as women have turned away from estrogen-replacement therapy, which has been linked with an increased risk of stroke (SN: 4/15/06, p. 228).

Epidemiologist Katherine M. Newton of the Group Health Center for Health Studies in Seattle and her colleagues recruited 351 women who responded to a mailed questionnaire seeking trial volunteers. The women, between the ages of 45 and 55, were each experiencing an average of seven hot flashes, including night sweats, per day.

The scientists randomly divided the volunteers into groups to receive one of five treatments: estrogen therapy, black cohosh, black cohosh and other supplements, the cohosh-supplement combination plus a daily serving of soy, or a placebo.

At the end of the 1-year trial, women getting estrogen therapy were having about two hot flashes per day. However, women taking the placebo or one of the black cohosh treatments still experienced on average four to five hot flashes daily, the scientists report in the Dec. 19, 2006 Annals of Internal Medicine.

Because the women volunteered for the trial, they "probably hoped there would be an effect" from black cohosh, Newton says. "If anything, that reinforces our finding."