Herbal Menopause Supplement Often Contains Other Species, DNA Bar Coding Reveals

Genetic analyses found herbs similar to black cohosh were being sold in commercial preparations of the popular remedy, possibly explaining mixed results and casting doubt on supplement label accuracy

By Katherine Harmon

A pure pill? Some black cohosh pills sequenced did not contain black cohosh at all, but rather entirely different plant species. Image: iStockphoto/OlgaMiltsova

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When hormone replacement therapy was found to put some menopausal women at increased risk of cancer and cardiovascular disease, many went in search of safer treatments to decrease their symptoms. In the ensuing decade black cohosh has won out as an overwhelming consumer favorite, now reaping millions of dollars in sales each year.

But controlled trials of this supplement have seen mixed results, sometimes showing it to be effective in relieving hot flashes, sleep disruptions, mood swings and other symptoms whereas other times revealing it to be ineffective. And some case reports even suggest that it can be toxic, damaging the liver.

This messy track record gave Damon Little, a bioinformaticist at The New York Botanical Garden (NYBG), and his colleagues an idea: What if patientsin these trials and out in the communitywere not always taking pure, actual black cohosh (Actaea racemosa), but one or more related species? Fortunately, they had just the tool on hand to figure that out: DNA barcoding.

Using this technology, which locates and sequences specific areas of a plant's genome (specifically, two matK gene nucleotides), they were able to determine that one quarter of commercially available "black cohosh" pills were not the herb at all. Their findings were published this July in the Journal of AOAC International.

"Misidentification and adulteration in black cohosh supplements [has been] known for many years as a matter of concern," notes Rolf Teschke, an internist at the Teaching Hospital of the Johann Wolfgang Goethe University in Frankfurt and who was not involved in the new research. "The present study confirmsbut extendsprevious findings."

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Herbal Menopause Supplement Often Contains Other Species, DNA Bar Coding Reveals