Research on Black Cohosh Supports Benefits in Menopause
Herb Science Group Shows Weaknesses of New Unpublished Study
Austin, TX (May 17, 2005). The popular herb black cohosh reduces hot flashes and other symptoms associated with menopause in most published clinical trials, said the American Botanical Council (ABC), a leading nonprofit herbal science organization.
ABC was responding to a press release issued May 15 summarizing an unpublished double-blind, placebo-controlled clinical trial on 132 women conducted by researchers at the Mayo Clinic in Scottsdale, Arizona.1 The researchers concluded that black cohosh pills used in their trial did not provide any noticeable benefit for menopause symptoms when compared to placebo. The findings are being reported at this weeks’ meeting of the American Society of Clinical Oncology in Orlando, Florida.
ABC stressed that there are numerous weaknesses and problems with the trial described in the press release from Mayo Clinic. For example, a full report describing the trial’s results has not yet been completed and subjected to the necessary peer-review process required for publication in a reputable medical journal. Further, the trial was only four weeks in length, probably too short to measure any effect from the product tested, since most clinical trials on black cohosh have run for three to six months. (The trial had a cross-over design, i.e., women took black cohosh or a placebo for four weeks, and then switched for another four weeks, after a brief “washout period.” Thus, the amount of time any group of women experienced the herb was four weeks, generally acknowledged by most black cohosh experts as being too short a period to produce a measurably beneficial effect.)
Another area of potential ambiguity in this trial is the black cohosh product employed. The researchers attempted to produce a replica of Remifemin®, the German black cohosh product with the most clinical research (see below), according to an email from Barbara Pockaj, MD, the principal investigator in the trial. Dr. Pockaj said that a smaller pilot trial that she conducted previously showed positive results when she used Remifemin but she was unable to obtain this product from its manufacturer for the larger trial now being reported. Consequently, she and her colleagues chose to try to produce a duplicate product. It is not clear to what extent the researchers were actually successful in replicating an exact match of Remifemin.
As the world’s leading black cohosh product, Remifemin has been shown effective in numerous clinical trials, including a larger and longer trial just published.2 This trial concluded that Remifemin was effective in relieving menopausal symptoms. The randomized, multicenter, double-blind, placebo-controlled trial on 304 menopausal women demonstrated that 40 mg of the German black cohosh preparation produced clinically significant benefits, particularly in women in early stages of menopause, with no significant adverse side effects.
“Most of the clinical trials published to date on black cohosh have demonstrated positive results in helping to treat various symptoms of menopause,” said Mark Blumenthal, founder and executive director of ABC. “The evidence supporting the benefits and relative safety of this traditional herb is becoming increasingly clear.”
Menopausal symptoms include the well-known hot flashes (sometimes called hot flushes), as well as night-time perspiration, vaginal dryness, and mood swings. According to ABC, several European black cohosh preparations have been shown to be effective in alleviating these conditions.
At least 14 clinical trials on black cohosh preparations support their safety and efficacy in treating menopause-related symptoms, including hot flashes, perspiration and mood swings, according to Gail Mahady, PhD, Assistant Professor of Pharmacy Practice at the University of Illinois at Chicago, who has reviewed most of the research on black cohosh for a monograph for the World Health Organization. Most of these published trials are based on the two leading black cohosh products: Remifemin® (an isopropranolic extract produced by the German company Schaper and Brümmer, and imported into the U.S. by GlaxoSmithKline) and Klimadynon® (a hydro-ethanolic [water and grain alcohol] extract produced by the German company Bionorica and imported by Bionorica USA).
Black cohosh, also known by either its scientific names (Actaea racemosa and Cimicifuga racemosa) is a member of the buttercup family (Ranunculaceae) native to the Eastern United States. The roots and rhizomes (lateral roots) of the herb have a long history of use by native American tribes to deal with genitourinary complaints in women. An extract of black cohosh has been used in German clinical practice since the mid-1950s with safe and effective results, and black cohosh preparations have been approved by the German government as nonprescription medications for treatment of menopausal symptoms.
Black cohosh has become increasingly popular as the most widely-used natural alternative to hormone replacement therapy (HRT). The herb’s popularity with middle-aged women and gynecologists grew significantly after the summer of 2003 when a large-scale government-sponsored clinical trial on HRT was halted prematurely after evidence that HRT was responsible for an increase in cancer and cardiovascular disease in menopausal women.
Black cohosh preparations ranked eighth of all herbal supplements sold in mainstream retail outlets in 2004, according to data from Information Resources in Chicago as reported in the current issue of HerbalGram, ABC’s quarterly journal. Total retail sales of black cohosh in all channels of trade are difficult to estimate, but may be as high as $76 million in 2003, a jump of about 28% in sales from the previous year, according to Nutrition Business Journal.
References
1 Mayo Clinic Researchers Report on Effectiveness of Treatments for Hot Flashes [press release]. Scottsdale, AZ: Mayo Clinic; May 15, 2005.
2 Osmers R, Friede M, Liske E, Schnitker J, Freudenstein J, Henneicke-von Zepelin H-H. Efficacy and Safety of Isopropanolic Black Cohosh Extract for Climacteric Symptoms. Obstet Gynecol 2005;105:1074-83.