THURSDAY, June 1, 2006 (HealthDay News) -- Women taking black cohosh supplements to ease the hot flashes of menopause may not always be getting what they pay for, a new study reveals.
Black cohosh, a plant native to North America that has traditionally been used to treat fatigue, kidney problems and menstrual irregularities, has been used by menopausal women in the United States and Europe for the past 40 years. Some studies have reported that black cohosh improves menopausal symptoms, including hot flashes, mood disturbances, palpitations and vaginal dryness, for up to six months.
But the compounds in black cohosh thought to alleviate hot flashes vary widely from product to product, if they are even present at all, say researchers reporting in the May issue of the Journal of Agricultural and Food Chemistry.
In this U.S. study, researchers analyzed 11 of the most popular black cohosh tablets and capsules available in New York City between 2002 and 2004. Using a process called high-performance liquid chromatography, they extracted, separated and identified the hundreds of different compounds within each black cohosh sample.
"We did anticipate some difference in the chemical profiles based on manufacturing and biological differences. But what was surprising was that three of the products that we evaluated didn't have black cohosh at all," said study author Edward Kennelly, of the City University of New York, in New York City.
These three supplements claiming to contain black cohosh instead contained an Asian species of Actaea. The Chinese herb is closely related to black cohosh but has not been proven effective in easing menopausal symptoms. To keep up with the increased demand for black cohosh products, supplement manufacturers may substitute Actaea for black cohosh, because it is less expensive to produce, the researchers postulated.
In their study, Kennelly and colleagues maintained that although Actaea is widely used in traditional Chinese medicine, it is not clear whether exchanging it or using it in combination with black cohosh is safe or effective.
Another expert said that the discovery that some black cohosh products contain Actaea does not necessarily render these supplements ineffective.
"There is no evidence yet that black cohosh is better for decreasing menopause symptoms than Asian Actaea. Therefore, if some products have the Asian version or a mix [of both compounds], that does not mean they are not going to be effective," said Dr. Ray Sahelian, author of Mind Boosters: A Guide to Natural Supplements That Enhance Your Mind, Memory and Mood.
Both Kennelly and Sahelian point out that no one is sure which compounds in black cohosh relieve the redness, sweating and pounding heartbeat commonly associated with hot flashes. Triterpene glycosides and phenolic constituents are two of the compounds in black cohosh that experts think may be responsible, but the amounts of these compounds varied widely in the study.
The researchers also discovered that, compared to black cohosh tablets, capsules tended to contain higher amounts of triterpene glycosides.
Because of the variability in product quality and the lack of government regulation when it comes to dietary supplements, consumers interested in using black cohosh to relieve menopausal symptoms may need to try more than one brand to find one that works for them.
"Since menopausal symptoms are not life-threatening and do not cause serious illness, a woman has time to experiment with different herbs or combinations to see what works for her best," Sahelian said.
The U.S. National Institutes of Health Office of Dietary Supplements has more information about black cohosh.