New studies question use of DNA barcoding to authenticate botanical dietary supplements.

  • In 2015, the New York Attorney General (NY AG) launched a high-profile investigation into the marketing of botanical dietary supplements, culminating in backlash against herbal supplements and a landmark settlement with a major supplement retailer.  However, the NY AG investigation was mired in controversy due to its lack of transparency and complete reliance on DNA barcoding as the apparent “gold standard” for assuring the identity and purity of herbal/botanical ingredients.
  • Earlier this month, new data were presented that call into question the utility of DNA barcoding by itself as a means of authenticating botanical ingredients in supplements.  Two new studies were presented by an FDA scientist (research coordinator for dietary supplements) and by an Australian research consortium at the 16th Annual Oxford International Conference on the Science of Botanicals.  The FDA data compared the results of high performance liquid chromatography (HPLC) analysis and DNA barcoding of five popular botanical ingredients.  When 112 products were analyzed using both techniques, the results indicated that 111 contained marker compounds. However, when the products were tested by DNA barcoding alone, only 31 of the 112 products were found to contain DNA from the labeled ingredient.  Similar conclusions were reached in the Australian study.
  • Although FDA has not taken an official position on the use of DNA barcoding as an authentication method, these data continue to call into question the validity of this method as applied to identifying botanical ingredients.  Industry experts have long claimed that DNA barcoding is not a suitable method for authenticating botanical extracts because DNA material in these components may be of low quality or degraded to a point that generates false negatives in analytical testing.  Although it is too early to tell how influential these new data will be in the context of regulatory enforcement and plaintiffs’ class action lawsuits against the supplement industry, they contribute empirical evidence to the debate over the appropriateness of overt reliance on barcoding alone in this area.