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Science Group Says Article on DNA Barcode Analysis
of Herbs Is Flawed, Contains Errors, Creates Confusion, and Should Be Retracted
Methodological
Flaws, Statistical Inconsistencies, Taxonomic Confusion, and Unreliable
Conclusions Require Paper in BMC Medicine to be
Corrected, Revised, and Re-peer-reviewed
(AUSTIN, Texas, Nov. 5, 2013)
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.1 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.2
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
November 5 “Science Times” section of the New York Times in an article that
raises questions about the quality of dietary supplements.3
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 today 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 —
president and CEO of AuthenTechnologies in Richmond, California — 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."
References
1.
Newmaster SG, Grguric M, Shanmughanandhan D, Ramalingam S, Ragupathy S. DNA
barcoding detects contamination and substitution. BMC Medicine.
2013:11:222 doi:10.1186/1741-7015-11-222.
2. Gafner S, Blumenthal M, Reynaud DH, Foster S, Techen N. ABC Review and
Critique of the Research Article “DNA Barcoding Detects Contamination and
Substitution in North American Herbal Products” by Newmaster et al.
HerbalEGram, November 2013. Available at: http://cms.herbalgram.org/heg/volume10/11November/DNAbarcodingReviewandCritique.html?t=1383684796.
3. O’Connor A. Herbal Supplements Are Often Not What They Seem. Science
Times, p. 1. New York Times, Nov. 5, 2013. Originally published online Nov.
3, 2013: Available at: http://www.nytimes.com/2013/11/05/science/herbal-supplements-are-often-not-what-they-seem.html?ref=science.
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