In 2002, the Women's Health Initiative (WHI) stopped its hormone therapy study because of potential health risks. These included increases in breast cancer, heart attack, and stroke. The WHI decision does not apply to women taking hormones for the relief of menopausal symptoms. However, it has spurred many to seek out natural alternatives to estrogen.
Some of the most popular are black cohosh, red clover, evening primrose oil, and phytoestrogens such as soy. But a review published in November 2002 found little evidence that any of them do much good. The one exception to these findings is black cohosh.
Researchers examined the results of 29 clinical trials of alternative and complementary products used for menopausal symptoms. They found that only black cohosh has any effect. In some studies, women who ate foods (such as tofu) or supplements containing phytoestrogens found some relief. Phytoestrogens are estrogen-like molecules from plants. But the benefits largely disappeared after six weeks, and in some of the studies, women taking a placebo fared as well as those receiving a phytoestrogen product.
Black cohosh, one of the most popular alternative treatments for menopausal symptoms, showed the greatest promise. In three of the four studies reviewed, it appeared to reduce hot flash frequency and intensity.
RemiFemin is the black cohosh product used in most published studies. It is available over-the-counter in the United States. And in Germany, where herbs are an integral part of conventional medicine, black cohosh is approved for both menstrual and menopausal discomforts. However, its mechanism of action is unknown.
In the March 2002, researchers funded by the manufacturer of RemiFemin reported on a six-month trial involving 150 peri- and postmenopausal women. Those taking the standard dose (40 mg/day) experienced a 70% reduction in symptoms. These included hot flashes, mood swings, night sweats, and occasional sleeplessness. Women on a higher dose (127 mg/day) got no additional relief. Side effects include mild stomach upset, low blood pressure, and — in high doses — headaches, vomiting, and dizziness.
Although the results so far are encouraging, most clinical studies have been brief and yielded inconsistent data. Also, different studies have used different doses and parts of the herb, making it difficult to compare results.
To help clarify matters, the National Center for Complementary and Alternative Medicine (part of the National Institutes of Health) has funded a 12-month trial at Columbia University. This study will compare the effects of black cohosh to a placebo in women ages 45–70. More information is available at http://www.clinicaltrials.gov/.
March 2003 Update