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What's in this Bottle?

Many people turn to herbal supplements like echinacea to ward off colds or St. John's wort to battle depression, but a recent DNA barcoding study in BMC Medicine indicates that such supplements may not always contain what's on their labels.

The researchers led by Subramanyam Ragupathy from the University of Guelph assembled a standard reference material barcode library based on some 100 herbs of known origin. Using that reference, they examined the contents of 44 herbal supplements from 12 companies as well as 50 leaf samples from 42 species.

Ragupathy and his colleagues report that about 60 percent of the products contain DNA barcodes from plants that were not listed on their labels, and 30 of the 44 products contained substitutions. For example, they note that one product labeled as St. John's wort only had barcodes from Senna alexandrina, an herbal laxative; a Ginkgo product was contaminated with black walnut; and many products appeared to contain rice, soy, wheat, or other fillers.

Only 2 of the 12 companies, the researchers add, had products that did not appear to include substitutions, contaminants, or fillers.

"I think it's shocking, but not surprising," says Graham Lord, director of the UK's National Institute for Health Research Comprehensive Biomedical Research Center, tells the New Scientist. The article notes that Lord's group recently showed that people taking herbal supplements from Asia may be at risk of kidney failure and bladder cancer.

"The level of regulation of herbal products is not good enough, but it's an intelligent idea that the authors suggest to use DNA barcoding to determine purity and really get to grips with the provenance," Lord adds.

The American Botanical Council, a group that supports the use of herbal supplements, says in a statement that the BMC Medicine study was flawed. Mark Blumenthal, the founder and executive director of ABC, argues that DNA barcoding is not an appropriate tool for analyzing processed herbal extracts.

In its statement, the group calls for the paper's retraction.