A controversial new study published in the journal BMC Medicine found that one-third of 44 herbal supplements tested showed no detectable amounts of the plant advertised on the bottle. The researchers used DNA barcoding, a type of genetic fingerprinting, to determine the contents of the herbal supplements manufactured from 12 companies representing 30 herb species and selected from Canadian and American stores. Big newspapers like The New York Times immediately published an article based on the study’s results called “Herbal Supplements are Often Not What They Seem.” But perhaps the article’s title should have been “14 Out of 44 Herbal Supplements Tested in One Study are Not What They Seem.”
According to the researchers they were able to authenticate almost half of the products—meaning the products contained exactly what was listed on the label in 48 percent of the product samples. In one-third of the products, ingredients not listed on the label were found in the product. The researchers refer to these ingredients as “contaminants and/or fillers.”
After reading the study I was surprised that the sample size was so small and that the New York Times made rather broad statements based on such a small sample. They even indicated that “many” of the products were adulterated with ingredients not listed on the label. Now, I’m not impressed by companies adding fillers to their products in any way but I don’t even think “many” herbal products were tested in this study so it would be impossible to state that “many” were adulterated.
When I tracked down the original study I was also surprised to discover it read more like a promotion for the DNA barcoding technology used and even went as far as to conclude that this technology should be used in herbal products regulation. I was curious because I read a lot of studies and rarely come across ones that read like product placements or advertisements for the technology used. When I checked the patents database on DNA barcoding technology I noticed that the University of Guelph is a co-applicant for the patent on “DNA barcode sequence classification”—the technology being promoted in this study.
The following statement constitutes part of the study’s “scientific” conclusions:
“We suggest that the herbal industry should embrace DNA barcoding for authenticating herbal products through testing of raw materials used in manufacturing products. The use of an SRM DNA herbal barcode library for testing bulk materials could provide a method for ‘best practices? in the manufacturing of herbal products.”
Apparently I’m not the only one worried about the study’s results. According to Stefan Gafner, Chief Science Officer at the American Botanical Council, an independent non-profit organization that provides science-based and traditional information to promote the responsible use of herbal medicine, the study was flawed. In the same New York Times article he indicated that it was flawed because the bar-coding technology could not always identify herbs that have been purified and processed.
As some background when specific extracts are derived from plants (as in the case of curcumin extracted from the herb turmeric), the herb may undergo processing to allow the extraction process.
He added that “Over all, I would agree that quality control is an issue in the herbal industry. But I think that what’s represented here is overblown. I don’t think it’s as bad as it looks according to this study.”
What You Can Do to Ensure Quality Herbal Products:
Remember that herbs were the primary medicine of humans for thousands of years. A study of 44 products from 12 companies is too small to rely on for valuable herbal recommendations.
Choose high quality products or raw herbal materials from a reputable company. These products can safely and easily be made into teas or other natural medicines.
Work with a qualified health practitioner knowledgeable in the field of herbal medicine.
Grow your own herbal medicines. While it is not possible with all herbs, many common herbs can be grown on a windowsill and used whenever needed, especially for herbal teas. It is much easier to identify the herb when it is still a full plant than when it has been dried, crushed, and added to capsules.