American Botanical Council Clarifies Importance of Ginkgo Toxicology Report
AUSTIN, Texas, April 18, 2013 /PRNewswire-USNewswire/ -- The nonprofit American
Botanical Council (ABC) says that clinically tested ginkgo extracts sold as
dietary supplements in the United States are safe for most consumers. The ABC
statement follows news of the publication of a report by the National Toxicology
Program that showed that a special formulation of a Chinese ginkgo extract
produced cancers in certain strains of rats and mice in a series of animal
toxicology studies performed over two years In the conclusion of the report, the
authors wrote, "We conclude that Ginkgo biloba extract caused cancers of the
thyroid gland in male and female rats and male mice and cancers of the liver in
male and female mice."1
In February 2012, ABC sent public comments to NTP for the authors of the ginkgo
study to consider in revising the draft report.2 The ABC comments were compiled
by a committee of medicinal plant science and toxicology experts.
ABC emphasized that the Chinese ginkgo extract manufactured in Shanghai is not
consistent with any compendial botanical and chemical standards for quality as
set forth in various official pharmacopeias and does not conform to the
well-established chemical profiles, quality, and purity of the leading,
clinically tested ginkgo extracts produced by the pioneering Willmar Schwabe
Pharmaceuticals of Karlsruhe, Germany, and Indena SpA in Milan, Italy. The
ginkgo used in the NTP study was manufactured by the Shanghai Xing Ling Science
and Technology Pharmaceutical Co., Ltd.
"The ginkgo extract used in this study is different from the high-quality ginkgo
extracts used in published clinical trials showing safety and various beneficial
activities of ginkgo," said Mark Blumenthal, founder and executive director of
ABC. "That is, the Shanghai ginkgo extract used by NTP does not represent the
quality of German ginkgo extract that is the world standard for ginkgo. It is
highly unfortunate that NTP chose to use this ginkgo extract as it means that
the results of the NTP's studies are not applicable to the standard-setting
In addition, ABC noted that the dosage levels administered to the test animals
was significantly higher (up to 55-108 times higher) than the levels of ginkgo
extract that are normally ingested by consumers (120-240 milligrams per day), as
calculated by ABC's consulting toxicologist.
"At best, what NTP can say is that significantly high doses of this particular
Shanghai Chinese ginkgo extract - when added to a corn-oil base - produced
cancer in the lab animals," added Blumenthal.
ABC emphasized that the NTP studies are not intended to imply the potential
adverse effect in humans.
"The NTP's public message, and the resulting media reports, totally miss this
point about the actual identity of the ginkgo extract and the high-dosage
levels, and will probably cause confusion among consumers and health
professionals alike," added Blumenthal.
"Almost anything will create cancer in rats and mice when it's fed to them at
high doses for two years," said Bill J. Gurley, PhD, professor of pharmaceutical
sciences in the College of Pharmacy at the University of Arkansas School for
Medical Sciences, Little Rock. "All toxicologists and pharmacologists are aware
of the susceptibility of certain strains of rodents used for research purposes
to develop various forms of cancer and other diseases when subjected to various
substances." Dr. Gurley was a co-author of the 2012 ABC public comments letter
"This is disappointing, to say the least," said Rick Kingston, PharmD, president
of regulatory and scientific affairs at SafetyCall International in Minneapolis,
MN, and professor of pharmacy at the University of Minnesota College of
"Notwithstanding major design flaws in the study in identifying an appropriate
compound to represent available ginkgo in the market," continued Dr. Kingston,
"even the reviewers voiced adamant proclamations that the results in this animal
research were not intended for direct extrapolation to humans. For this
oversight to not be reconciled by the NTP review group is disconcerting,
especially since misinterpretation of the results by well-intentioned, but
scientifically unsophisticated media outlets, and possibly even consumer groups,
should have been an expected outcome." Dr. Kingston also was a co-author of the
public comments letter from ABC to NTP.
The ABC comments sent to NTP as part of the public comment process also called
attention to other anomalies and/or problems with the NTP ginkgo studies as
noted in the draft report. These include concerns that the Shanghai ginkgo
extract used in the NTP study was from several different production batches, and
that the ginkgo extract material used in the study was not analyzed for the
presence of potential contaminants.
1. National Toxicology Program. NTP Technical Report on the Toxicology and
Carcinogenesis Studies on Ginkgo Biloba Extract (CAS NO. 90045-36-6) IN F344/N
Rats and B6C3F1/N Mice. (Gavage Studies). March 2013. Available at:
2. Blumenthal M, Gurley BJ, Kingston R, Low Dog T, Mackay D. American Botanical
Council Revised Comment on NTP Draft Toxicology Report on Ginkgo Biloba Extract.
Feb. 7, 2012. Available at:
About the American Botanical Council
Founded in 1988, the American Botanical Council is a leading international
nonprofit organization addressing research and educational issues regarding
herbs, teas, medicinal plants, essential oils, and other beneficial
plant-derived materials. ABC's members include academic researchers and
educators; libraries; health professionals and medical institutions; government
agencies; members of the herb, dietary supplement, cosmetic, and pharmaceutical
industries; journalists; consumers; and others in more than 81 countries. The
organization occupies a historic 2.5-acre site in Austin, Texas, where it
publishes the peer-reviewed quarterly journal HerbalGram, the monthly
e-publication HerbalEGram, the weekly e-newsletter Herbal News & Events,
HerbClips (summaries of scientific and clinical publications), reference books,
and other educational materials. ABC also hosts HerbMedPro, a powerful herbal
database, covering scientific and clinical publications on more than 250 herbs.
ABC also co-produces the "Herbal Insights" segment for Healing Quest, a
television series on PBS.
ABC is tax-exempt under section 501(c)(3) of the IRS Code. Information: Contact
ABC at P.O. Box 144345, Austin, TX 78714-4345, Phone: 512-926-4900. Website:
www.herbalgram.org. Contact: Public Relations.
SOURCE American Botanical Council