The ABC-AHP-NCNPR Botanical Adulterants Prevention Program (BAPP) has published a new Laboratory Guidance Document (LGD) on ginkgo (Ginkgo biloba, Ginkgoaceae) leaf extracts.
Ginkgo leaf extracts are used widely around the world to improve mental performance, for circulatory issues such as peripheral arterial occlusive disease, and for vertigo and tinnitus. In the United States, ginkgo leaf extract dietary supplements have been consistently among the 25 top-selling herbal supplements, with more than $33 million in sales in 2020 in the natural and mainstream channels combined.1
Over the past 20 years, at least 27 publications in the peer-reviewed scientific literature have documented cases of adulteration of ginkgo leaf extract ingredients and finished products. Such adulteration generally involves the addition of undeclared flavonol-rich ingredients or highly purified flavonoids (e.g., quercetin or rutin) from lower-cost sources, most commonly extracts or purified fractions of the flowers and leaves of Japanese sophora (Styphnolobium japonicum syn. Sophora japonica, Fabaceae). Of the 501 samples analyzed in these 27 papers, 242 (48%) were considered to be adulterated according to criteria established by the authors of each of these publications, suggesting that ginkgo leaf extract adulteration is widespread.
Undeclared added materials typically are rich in rutin and/or quercetin to increase the extract content of flavonol glycosides to 24%, the minimum amount specified on the labels of most commercial dietary supplements to meet the same standardization requirement as the extract EGb 761® (Dr. Willmar Schwabe GmbH & Co. KG; Karlsruhe, Germany), the most clinically tested ginkgo leaf extract in the world. Since both rutin and quercetin also are found in ginkgo leaves, detecting adulteration of commercial ginkgo materials can be challenging.
The LGD assesses the usefulness of 78 laboratory analytical methods to authenticate ginkgo leaf extract and/or detect ginkgo leaf extract adulteration. The document was written by Stefan Gafner, PhD, chief science officer of the American Botanical Council (ABC) and technical director of BAPP. Thirty experts from academia, government, and the herbal dietary supplement industry in the United States and internationally reviewed the LGD.
Gafner explained: “Finding a suitable analytical method to authenticate ginkgo leaf extracts is time-consuming at least in part because of the large number of methods available in the peer-reviewed literature, national pharmacopeias, and other official compendia. Not many botanical ingredients have been the subject of such a vast body of analytical work dedicated to its quality control. We hope that this is where the ginkgo LGD can be valuable to the international medicinal plant community since it provides an overview of relevant, reliable, and fit-for-purpose methods in a single document.”
Mark Blumenthal, founder and executive director of ABC and founder and director of BAPP, said: “Standardized ginkgo leaf extract is one of the most clinically researched phytomedicinal products in the world. Many consumers purchase ginkgo products and health care practitioners sometimes recommend them in the hope that these products will deliver a clinically documented health benefit. However, if the product contains an intentionally adulterated extract, it is not likely that it will produce the health benefits observed in published clinical trials. Adulteration of ginkgo, or any herb product, is a great disservice to the millions of people who wish to improve or maintain their health naturally.”
The ginkgo leaf extract LGD is the 13th publication in the series of LGDs.
About the Botanical Adulterants Prevention Program
The ABC-AHP (American Herbal Pharmacopoeia)-NCNPR (National Center for Natural Products Research at the University of Mississippi) Botanical Adulterants Prevention Program is an international consortium of nonprofit professional organizations, analytical laboratories, research centers, industry trade associations, industry members, and other parties with interest in herbs and medicinal plants. The program advises industry, researchers, health professionals, government agencies, the media, and the public about various challenges related to adulterated botanical ingredients sold in commerce. To date, more than 200 US and international parties have financially supported or otherwise endorsed the program. BAPP has published 73 extensively peer-reviewed articles, including Botanical Adulterants Prevention Bulletins, LGDs, and Botanical Adulterants Monitor e-newsletters.
- Smith T, Majid F, Eckl V, Morton Reynolds C. Herbal supplement sales in US increase by record-breaking 17.3% in 2020. 2021(131):52-65. Available at: www.herbalgram.org/resources/herbalgram/issues/131/table-of-contents/hg131-mkrpt/. Accessed April 18, 2022.