Treating Symptoms of Menopause: A Study of the Effectiveness of Black Cohosh Alone and with Other Herbal Therapies or Soy

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The summary below is from the full report titled "Treatment of Vasomotor Symptoms of Menopause with Black Cohosh, Multibotanicals, Soy, Hormone Therapy, or Placebo. A Randomized Trial." It is in the 19 December 2006 issue of Annals of Internal Medicine (volume 145, pages 869-879). The authors are K.M. Newton, S.D. Reed, A.Z. LaCroix, L.C. Grothaus, K. Ehrlich, and J. Guiltinan.

What is the problem and what is known about it so far?

During and around the time of menopause, levels of the hormones estrogen and progestin decrease. Hot flashes and night sweats (also called vasomotor symptoms) are the menopausal symptoms that many women find most troublesome. These symptoms can begin before menstrual periods stop and persist for months to years afterward. Hormone therapy, which involves taking estrogen with or without progestin, reduces vasomotor symptoms. Before the 2002 publication of the results of a study called the Women's Health Initiative (WHI), research suggested that the benefits of hormone therapy outweighed the risks associated with it. However, the study showed that women who received hormone therapy actually had a higher risk for heart disease, stroke, and some types cancer than women who did not receive hormone therapy. As a result, other treatments for vasomotor symptoms are needed. The use of natural or herbal therapies has become popular among women with menopausal symptoms. Unfortunately, good studies about the effectiveness and safety of natural therapies in treating vasomotor symptoms are lacking.

Why did the researchers do this particular study?

To find out whether any of 3 types of natural therapies (black cohosh, multibotanicals, or multibotanicals with an increased intake of foods containing soy) reduce menopausal hot flashes and night sweats.

Who was studied?

351 women aged 45 to 55 years who had at least 2 episodes of hot flashes or night sweats per day. About one half of the women were in the process of menopause, and one half had completely stopped having menstrual periods.

How was the study done?

The researchers assigned the women at random to receive 1 of the following treatments: 1) 160 mg/d of black cohosh; 2) a multibotanical herbal product containing 200 mg of black cohosh plus 9 other herbal ingredients (alfalfa, boron, chaste tree, dong quai, false unicorn, licorice, oats, pomegranate, and Siberian ginseng); 3) a multibotanical herbal product plus counseling to increase intake of foods containing soy; 4) hormone therapy; or 5) a placebo pill—that is, a pill containing no active ingredient. The hormone therapy and placebo groups were included as comparisons of known effective and ineffective treatments. The women reported the frequency and severity of hot flashes and night sweats at the start of the study and at 3, 6, and 12 months during the study. The researchers compared the changes in symptoms over the course of the study in each group.

What did the researchers find?

As expected, women who took hormone therapy had fewer symptoms than those who took placebo. The frequency and severity of symptoms in women who took any of the natural therapies were similar to those of women who took placebo.

What were the limitations of the study?

The study was too small to detect small changes in symptom frequency (less than 1.5 hot flashes per day). The herbal products were given without counseling by a natural healer.

What are the implications of the study?

Black cohosh, a multibotanical herbal product, and increased soy intake do not appear to reduce the frequency or severity of menopausal hot flashes or night sweats.