DNA Barcoding Inadequate to ID Botanical Extracts: NPA White Paper

The DNA barcoding method that the New York Attorney General used to send cease-and-desist letters to four retailers in New York is not adequate to test the identity of botanical extracts, according to a white paper released by the Natural Products Association (NPA).

According to the tests from New York Attorney General Eric Schneiderman, many store-brand botanical products did not contain the botanicals that were noted on the label. Additionally, the Attorney General said the tests found contaminates such as asparagus, beans and pine.

“The use of DNA barcoding methodology on extracts of raw ingredients is neither a good, better or best standard of practice in the dietary supplement industry," wrote Daniel Fabricant, Ph.D., former Director of the Division of Dietary Supplement Programs at FDA and current CEO of NPA; and Corey Hilmas, M.D., Ph.D., former Chief of the Dietary Supplement Regulation Implementation Branch at FDA and NPA’s senior vice president of scientific and regulatory affairs. “Moreover, if the study actually was scientifically valid and fit for purpose, the science would appear to be inconsistent with the dietary supplement current good manufacturing practices (cGMPs)."

In the white paper “DNA Barcoding for Botanical Authentication", Fabricant and Hilmas, argued that the tests the New York Attorney General used were likely not fit for purpose for identifying botanical ingredients in the products they tested. However, the authors wrote, the exact methods his office used aren’t clear because he has not released the data, despite repeated requests to do so.

The New York Attorney General did say he used DNA Barcoding to test the products, which Fabricant and Hilmas said can be flawed due to the processed nature of products made from botanical extracts. “There are multiple steps in the manufacture of botanical dietary supplements between farming and final processing which degrade DNA," they wrote. These treatment can cause the DNA strains to break and be unrecognizable in barcoding tests.

The NPA authors noted the lack of a robust DNA reference library to compare specimens to.  Reference libraries allow researchers to compare test results against established markers that show botanical identifies. “All we can conclude at this point is that he used publicly available DNA sequences that did not involve voucher specimens, leading to erroneous results," they wrote.

DNA testing shouldn’t have been conducted alone, they noted. They should have been partnered with chemical methods, such as chromatographic and spectroscopic assays, to authenticate the results. “Chromatographic methods are the gold standard as stand-alone methods for the identification of botanicals in diverse matrices such as finished dietary supplement products," they said.

Further, Fabricant and Hilmas noted that contamination of DNA can readily occur in facilities that aren’t ISO accredited; the lab that conducted the study at Clarkson University does not have such accreditation, according to the white paper. “It is therefore quite possible that the Clarkson University laboratory was the source of contaminants reported by the New York Attorney General."

NPA took the opportunity to again call for the Attorney General to release the data he used to send the cease-and-desist notices. “It is imperative that the attorney general or Clarkson University release the study report and accompanying data to either exonerate or debunk the study. All we can say at the moment is that the Clarkson University test results are preliminary and fail to provide a degree of certainty until they are validated with substantiation."

A separate white paper commissioned by four trade associations representing the dietary supplement industry was released last week that also noted DNA testing of botanical products is in its infancy, which has led to confusion and misuse of test results.

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