December 2006

NIH: Black cohosh not effective

The herbal supplement black cohosh, whether used alone or with other botanical supplements, did not relieve hot flashes in postmenopausal women or those approaching menopause, who participated in the Herbal Alternatives (HALT) for Menopause Study, according to results from the clinical trial.

The research, funded by the National Institutes of Health (NIH), found that women using menopausal hormone therapy, however, did receive significant relief from their hot flashes and night sweats.

The 12-month randomized, double-blind, placebo-controlled trial, compared several herbal regimens and menopausal hormone therapy (estrogen with or without progesterone) to placebo in women ages 45 to 55.

The HALT Study was conducted by Katherine M. Newton, PhD, of the Group Health Center for Health Studies, Seattle, and the University of Washington, and colleagues. The National Institute on Aging (NIA) and the National Center for Complementary and Alternative Medicine (NCCAM), two components of NIH, funded the research. The findings are reported in the Dec.19, 2006, issue of Annals of Internal Medicine.

Three-hundred and fifty-one women, ages 45 to 55, took part in the HALT Study, conducted at the Seattle-based Group Health Center for Health Studies. Each participant was experiencing at least two hot flashes and/or night sweats daily at the start of the study.

The women were approaching menopause, having missed at least one menstrual cycle in the preceding 12 months, or were postmenopausal, having had no menstrual cycle in at least 12 months. Researchers included women who were perimenopausal (or in the menopause transition) because most previous studies looked only at postmenopausal women, who tend to have fewer symptoms than women going through menopause.

Initially, the women were randomly assigned to receive one of five therapies:

• Black cohosh;

• A multi-botanical supplement, including black cohosh, alfalfa, boron, chaste tree, dong quai, false unicorn, licorice, oats, pomegranate and Siberian ginseng;

• A multi-botanical supplement plus diet counseling to increase consumption of foods containing soy;

• Menopausal hormone therapy, consisting of estrogen with or without a progestin;

• A placebo, containing no drug or supplement.

Participants met with clinic staff at three, six, and 12 months after the beginning of the study and also received monthly telephone calls from study nurses.

Newton and colleagues found no significant difference between the number of daily hot flashes and/or night sweats in any of the herbal supplement groups when compared to the placebo group. At the end of one year, the average difference was less than 0.6 symptoms per day. However, the average difference at one year in symptoms between the menopausal hormone therapy and placebo group was significant — 4.06 fewer symptoms per day among women receiving hormones.

“While this study found that black cohosh alone or with other herbs did not reduce menopausal hot flashes,” said NCCAM Acting Director Ruth L. Kirschstein, MD, “it highlights the importance of studying herbs using well-designed research to find out what works and what does not. With this information women and their physicians can have a meaningful discussion of complementary and alternative medicine approaches to menopause.”

Source: National Institutes of Health, www.nih.gov/news/pr/dec2006/nia-18.htm.

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