No colchicine in ginkgo: Independent testing refutes results of flawed research

Independent analyses of raw powdered Ginkgo biloba and ginkgo extract have discredited a recent study suggesting that ginkgo supplements contain the toxic alkaloid colchicine. The flawed study, "Identification of Colchicine in Placental Blood from Patients Using Herbal Medicines," by Petty et al., was released on the American Chemical Society's website on August 4, 2001, but apparently has not yet been formally published. The authors of the study warn that consumption of ginkgo supplements by pregnant women may pose dangers to developing fetuses, based on an analysis that they believe revealed the presence of colchicine in ginkgo.

Major media sources have publicized the study's conclusions, but herb experts and other scientists have strongly criticized the validity of the conclusions and the research methods used by the researchers. Some have suggested that the investigators misidentified a non-toxic ginkgo compound as colchicine. This ginkgo compound reportedly has a structure similar to that of colchicine, and the researchers failed to perform a test necessary to differentiate between the two. "Ginkgo simply does not contain colchicine," said HRF President Rob McCaleb. "These scientists should have done their homework before submitting their erroneous conclusions for publication."

Ginkgo has been the subject of hundreds of clinical, pharmacological, chemical, and toxicological studies, not a single one of which has identified colchicine as a gingko constituent. "For the authors to say 'such supplements should be avoided by pregnant women or those trying to conceive because the colchicine in them could affect the viability of a fetus,' as quoted in Chemical and Engineering News, is an unacceptable leap, give the questions raised about this report, and its conflict with the existing scientific literature with colchicine," said John Cordaro, president and chief executive officer of Council for Responsible Nutrition (CRN). Both CRN and the American Herbal Products Association (AHPA) commissioned third party analyses of finished ginkgo products sold in the US. Colchicine has not been detected in any of the products.

In addition, a comprehensive search of the scientific literature on ginkgo conducted by Dr. Norman Farnsworth, Distinguished Research Professor of Pharmacognosy at the University of Illinois at Chicago, further confirmed that colchicine has never been detected in ginkgo or ginkgo products. "Anyone who thinks that colchicine can be found naturally in ginkgo is not qualified to be a peer reviewer of this paper," Farnsworth said. -Evelyn Leigh