A chemical analysis of 11 commercially available products marketed as black cohosh found that three did not even contain the herb, which is grown in North America. Instead, researchers say, these products contained a related Asian species of the plant that differs not only chemically but also in its clinical uses compared with the North American species. Importantly, the imposter is also cheaper to produce.
One other product contained both the genuine black cohosh and the Asian imitator. And the seven products that contained only black cohosh had widely varying amounts of the compounds thought to be the active agents for the relief of menopause symptoms.
The findings are published in the May 17 issue of the Journal of Agricultural and Food Chemistry.
"The variability between products with black cohosh wasn't too surprising, but the fact that some of these products did not even contain black cohosh was both surprising and worrisome," says researcher Edward J. Kennelly, PhD, of Lehman College and the City University of New York.
Kennelly tells WebMD that the tested products were found in stores in New York City between 2002 and 2004 and were thought to be representative of what was available in the area at the time.
The researchers used a sophisticated testing technique to determine if the products contained black cohosh or the related Asian species.
Although the Asian plant has been used in Chinese medicine for centuries, Kennelly says it is not used for the same indications as black cohosh.
The researchers did not identify the 11 products they tested by brand, but they did notify the FDA of their findings, Kennelly says.
A spokesman for a leading trade group for the botanical products industry tells WebMD that the group was made aware a little over a year ago that some extracts used in the manufacture of black cohosh supplements did not contain genuine black cohosh.
Steven Dentali, PhD, says a manufacturer warned the American Herbal Products Association (AHPA), and the group quickly took action to make sure other manufacturers knew that the extracts were out there.
It has also identified an inexpensive method that can be used by the industry to identify the cheaper Asian extracts.
Dentali is vice president of scientific and technical affairs for the AHPA.
How Can Consumers Tell?
While it isn't always easy for consumers to know what they are getting when they buy botanical products like black cohosh, Dentali says herbal products that seem too cheap may be suspect.
"It is true that sometimes you do get what you pay for," he says. "Most of the better-known brands have invested in making sure that their supply chain is secure. They would not dream of buying extracts from questionable sources to manufacture their products."
The best known and best-selling black cohosh supplement now available is Remifemin, marketed by Enzymatic Therapy Inc. of Green Bay, Wis.
It is also one of the few products to have been tested in clinical trials, says Pam Boggs, who is a spokeswoman for the North American Menopause Society.
Boggs tells WebMD that the findings have been mixed, but some studies do suggest that Remifemin does relieve mild hot flash symptoms in perimenopausal women.
"We rarely mention brand names, but this is one time when we will," she says. "The Remifemin formulation has been studied, and we don't know of any other formulations that have undergone the same degree of scientific scrutiny."
But Boggs adds that none of the herbal supplements or other over-the-counter products has been shown to be effective for severe hot flash symptoms.
Estrogen therapy is still the best treatment for more severe hot flashes and other menopausal symptoms, but not all women can take them.
"The prescription medications work for many women, but they all have their own side effects," Boggs says. "There is no free lunch."