DNA barcoding study retracted by BMC Medicine

A 2013 study published in BMC Medicine titled “DNA barcoding detects contamination and substitution in North American herbal products,” has been retracted by the publication’s editor. The retraction note from BMC Medicine states, “The Editor has retracted this article. An investigation by the University of Guelph has found evidence of data fabrication in relation to this article. The Editor therefore no longer has confidence in the presented data. Steven Newmaster, Dhivya Shanmughanandhan, Subramanyam Ragupathy and Sathishkumar Ramalingam disagree with this retraction. Meghan Grguric has not explicitly stated whether they agree with this retraction.”

This is not the first study co-authored by Steve Newmaster to be retracted. A 2014 study was retracted in June of 2021 after that study’s co-author, Ken A. Thomas, raised concerns about the source of the study’s data and its reproducibility, actively disavowing the study he co-authored. That episode called into question Newmaster’s integrity as a researcher and led to an investigation by the University of Guelph for scientific misconduct. Newmaster was found not guilty by the institution. According to a report published in Science, the chairman of the panel conducting the investigation, John Walsh, wrote that despite “displaying a pattern of poor judgement and failed to apply the standards reasonably expected in research activity in his discipline,” there was “insufficient evidence” to find Newmaster guilty of misconduct.

Both of these studies made the case for DNA barcoding as a more reliable and cost-effective method of identifying plant species than traditional morphology-based taxonomic practices. The retracted 2013 study became the basis for New York Attorney General Eric Schneiderman’s decision to issue cease and desist letters to makers of devil’s claw supplements sold in the state, leading to negative press challenging the quality and integrity of the herbal products industry and greater regulatory burden on dietary supplement companies. According to the retracted 2013 study, researchers found DNA barcodes from plant species not listed on the labels of 59% of 44 herbal products sampled, as well as contaminants and fillers not listed on labels of one third of these products.

Industry has long been critical of the study and its methodology, pointing out its inaccuracies and expressing skepticism about the accuracy of a novel and yet unproven analytical tool. The American Botanical Council published an in-depth review critiquing the study in HerbalGram.