A recently published article that presents research conducted using DNA barcode technology to analyze various herbal products in North America contains numerous flaws, calculation errors, taxonomic anomalies, and unreliable conclusions, and should be retracted by the journal and appropriately corrected before it is republished. So says the American Botanical Council (ABC), an independent nonprofit research and education organization that recently published a critique of the paper co-authored by five herb quality control experts.
The paper, based on DNA technology, was published in October in the journal BMC Medicine. It has been cited by various media outlets, including the Nov. 5 “Science Times” section of the New York Times in an article that raises questions about the quality of dietary supplements.
ABC emphasizes that DNA technology, in general, is reliable when used appropriately. “We have published two articles in our peer-reviewed journal HerbalGram discussing the merits and benefits of DNA-based analytical methods for establishing the accurate identity of plant material, including botanical materials found in herbal teas, as well as dried powders in numerous capsules and tablets found in herbal dietary supplements and related products,” said Mark Blumenthal, founder and executive director of ABC, and a co-author of ABC’s critique.
“However,” added Blumenthal, “DNA-based analysis is not appropriate when used in some of the ways that the authors appear to have done so, i.e., when trying to use DNA to determine the identity of commercial herb products that may contain plant extracts. It is not clear from the DNA paper whether some of the commercial herb capsules analyzed by the Canadian researchers contained dried powdered herb extracts or not. If they did, then DNA sequencing would not reveal the identity of the labeled plant extract, and might provide confusing results based on other excipient and ‘filler’ ingredients, or contamination with other DNA that also may be in the capsule.”
ABC Chief Science Officer Stefan Gafner, PhD, was interviewed by New York Times reporter Anahad O’Connor for the Times article. During the approximately 15-minute interview, Dr. Gafner enumerated many of the paper’s inconsistencies, errors, and potential flaws, none of which were reported by the Times, except for the writer’s not confusing Latin names for the herb feverfew, unlike the authors of the DNA paper.
“The article published in the New York Times, as well as other media stories on this subject, appears to have totally overlooked many of this paper’s problems and inconsistencies that we have enumerated in our critique,” said Dr. Gafner. The ABC critique lists 10 problems, errors, and areas of confusion in the DNA paper.
The ABC critique also is co-authored by Danica Harbaugh Reynaud, PhD—resident and CEO of AuthenTechologies in Richmond, Calif.—and Natascha Techen, PhD, of the National Center for Natural Products Research (NCNPR) at the University of Mississippi. Both Drs. Reynaud and Techen are experienced in using DNA technology to identify botanical materials, particularly those in herbal teas and dietary supplements.
ABC’s Blumenthal added that ABC and some of its nonprofit herb expert associates have taken leadership in the United States in the past three years in helping to bring to the herb and dietary supplement industry’s attention the problem of accidental and intentional adulteration of herbal raw materials. ABC is the managing partner in an international consortium of independent analytical laboratories, nonprofit organizations, industry companies, trade associations, and others who are supporting the ABC-AHP-NCNPR Botanical Adulterants Program, which ABC is conducting with the nonprofit American Herbal Pharmacopoeia (AHP) and the NCNPR at the University of Mississippi. The NCNPR is a Center of Excellence with the US Food and Drug Administration. It analyzes botanical ingredients on contract for the FDA and develops laboratory analytical methods for determining proper identity and the possible presence of contaminants and/or adulterants in botanical raw materials and extracts.
Dr. Gafner, lead author of the ABC critique, is the technical manager of the Botanical Adulterants Program. Botanist Steven Foster, another critique co-author, is Chair of the ABC Board of Trustees and the author or co-author of four of the five extensive, highly peer-reviewed papers on adulteration of herbs published in HerbalGram by the Botanical Adulterants Program.
The ABC paper ends with the following statement, calling for revision of the DNA paper:
“[I]n our view, and in the opinion of expert reviewers of this critique, and with all due respect to the authors and BMC Medicine, the journal should retract this paper, and require that the authors address various errors and ambiguities by appropriately rewriting, correcting, and resubmitting it to the journal. The editors of the journal should then submit the corrected revision to an appropriate peer-review process that employs numerous expert reviewers (not just the two who presumably reviewed the initial paper) who are knowledgeable not only in the fields of DNA testing, but also botanical analytics, and related disciplines. Only then, if the paper passes such appropriately expanded peer review, should the paper be republished. Until then, despite the good intentions of its authors, this paper creates confusion, promotes false conclusions, and, unfortunately, may constitute a disservice to scientific researchers and other responsible members of the botanical products community."