The widely used herbal remedy black cohosh does nothing to eliminate hot flashes, night sweats and other symptoms of menopause, either alone or in combination with other herbs, federally sponsored researchers reported Monday.
Thousands of women use the supplement, but a controlled trial reported in the Annals of Internal Medicine showed it was no more effective than a placebo. Only estrogen significantly reduced hot flashes.
"In the doses we used, and the way we used it, it did not work," said epidemiologist Katherine M. Newton of Group Health, a health system based in Seattle, who led the study. "The findings will certainly be a disappointment to women. It would have been nice to find something that is safe and effective."
The study was sponsored by the National Institute on Aging and the National Center for Complementary and Alternative Medicine, both components of the National Institutes of Health.
Dr. Carol M. Mangione of UCLA's Geffen School of Medicine wrote in an editorial accompanying the study that physicians and women will have to look elsewhere for help, and unfortunately there are few alternatives.
About 2 million American women turn 50 each year, and about 80% of them have at least some symptoms of menopause.
A 2002 federal study showed that women who underwent estrogen replacement therapy had an increased risk of breast cancer and heart disease. For many women, black cohosh has become the primary alternative to hormone therapy.
Newton and her colleagues studied 351 women, age 45 to 55. Half were in the midst of menopause and half were post-menopausal. They averaged about six symptoms per day.
The women were divided into five groups. One group got 160 milligrams a day of black cohosh. A second group got a mixture of nine herbs plus 200 milligrams of black cohosh per day. The third got the herb mixture and were encouraged to eat more soy foods. The fourth got estrogen, with or without progestin. And the fifth got a placebo.
Women receiving either black cohosh or the herb mixture had an average reduction of 0.5 symptoms per day compared with those in the placebo group, a statistically insignificant finding.
Women receiving estrogen, in contrast, had a reduction of four symptoms per day. Those consuming soy actually had more symptoms, for reasons that are not clear.
The good news, Newton said, is that over the year, symptoms in the placebo group were gradually reduced by about 30%.
"The really strong message we need to get out is that menopause is a natural event, it is not an illness, and the symptoms are self-limiting," said Newton, who is not affiliated with any supplement or hormone manufacturer.
If the symptoms are too powerful, then women should take hormones in the lowest dose possible and for the shortest time possible, she said.