New York: Women who use the herbal supplement black cohosh may be using a fake supplement, according to an investigation by the American Chemical Society.

The herb, which is a native American plant, is used by millions of women to prevent some of the nasty symptoms of the menopause such as hot flushes. But in many cases it does not work.

But a new study, publication in the Journal of Agricultural & Food Chemistry, says that many black cohosh supplements do not contain black cohosh and may contain an Asian species of the plant which does not work as well.

The researched analysed 11 products marketed as black cohosh and found that three contained the Asian herb, one contained both herbs and others contained different amounts.

Researcher Edward Kennelly, PhD, who headed the study with Fredi Kronenberg, PhD said their finding revealed that many manufacturers are not following good best practice and was a warning to consumers..