The ABC-AHP-NCNPR Botanical Adulterants Prevention Program (BAPP) has released a Botanical Adulterants Bulletin on ginkgo (Ginkgo biloba) leaf extracts.

Ginkgo is one of the most important medicinal plants worldwide. The leaf extracts are used mainly to improve mental performance, for circulatory issues such as peripheral arterial occlusive disease, and for vertigo and tinnitus. Ginkgo leaf extract dietary supplements have been consistently among the 25 top-selling herbal supplements in the United States for more than a decade. 
 
Reports on ginkgo extract adulteration date back to 2003, when researchers observed uncharacteristically high amounts of the flavonoid rutin in a sample of bulk material. The addition of flavonoids from extraneous sources, which attempts to bring these “ginkgo” extracts in compliance with the 24% flavonol glycoside content standardization required by various pharmacopeial standards, has been confirmed in numerous subsequent papers. The ginkgo bulletin is the second publication by the program on ginkgo adulteration. In 2016, the BAPP published a review in HerbalGram of 11 laboratory analytical studies that documented ginkgo extract adulteration. 
 
The new bulletin, written by Stefan Gafner, PhD, chief science officer of the American Botanical Council (ABC) and technical director of the BAPP, lists the known adulterants, details analytical approaches to detect adulterants, and provides information on the cultivation, harvest, and market importance of ginkgo. The ginkgo extract bulletin has been peer-reviewed by 20 experts from academia and industry.

“Ginkgo leaf extract is one of the world’s most heavily researched phytomedicines,” said Mark Blumenthal, founder and executive director of ABC and BAPP. “Millions of consumers utilize ginkgo extracts for a range of health reasons based on frequently positive outcomes from published clinical trials. However, the ginkgo products that they are buying, if they are adulterated, may not be adequate to perform as well as those ginkgo extracts shown effective in the clinical research. As in many cases of adulteration and fraud, this creates a disservice to the public.”
 
Dr. Gafner commented: “Adulteration appears to be frequent, with some researchers reporting that over 70% of the samples tested do not contain authentic ginkgo leaf extract. In some instances, the ginkgo extract is entirely substituted with a flavonol-rich extract, such as a Japanese pagoda tree [Styphnolobium japonicum] flower extract. More often, though, pure flavonols or flavonol-rich extracts are mixed with ginkgo extracts to produce, or to attempt to produce, a constituent profile that complies with many pharmacopeial standards of 24% flavonol glycosides and 6% diterpene lactones.”
 
He added: “Ginkgo adulteration has become rather sophisticated. For some of the commercial samples, it is difficult to determine if the ginkgo extract is adulterated, or if the discrepancies from the regular ginkgo leaf extract fingerprint are due to differences in the manufacturing process or inadequate storage conditions.” 
 
The goal of the Botanical Adulterant Bulletins is to provide accounts of ongoing issues related to botanical identity and adulteration, thus allowing quality control personnel and lab technicians in the herbal medicine, botanical ingredient, dietary supplement, cosmetic, conventional food, and other industries where botanical ingredients are used to be informed on adulteration problems that are apparently widespread and/or that may imply safety concerns. 
 
The ginkgo bulletin is the 13th publication in the series of Botanical Adulterants Bulletins and the 38th peer-reviewed publication published by the program. As with all publications in the program, the bulletins are freely accessible to all ABC members, registered users of the ABC website, and all members of the public on the program’s website (registration required).