Ginkgo adulteration has become ‘rather sophisticated,’ says herbal expert

By Adi Menayang

- Last updated on GMT

Getty Images / macroart
Getty Images / macroart

Related tags Ginkgo

For more than a decade, supplements with ginkgo leaf extract have ranked in the top 25 of the most popular herbal supplements in the US, but adulteration of the ingredient has become rather sophisticated, said Dr. Stefan Gafner, PhD, chief scientific officer of the American Botanical Council (ABC).

“There have been many papers over the past 15 years on ginkgo extract quality issues and ginkgo leaf extract adulteration,”​ Gafner told NutraIngredients-USA.

The ingredient was highlighted in the latest bulletin released under the newly renamed Botanical Adulterants Prevention Program​, an initiative sponsored jointly by the American Botanical Council, the American Herbal Pharmacopoeia, and the National Center for Natural Products Research at the University of Mississippi.

According to the bulletin, reports on adulteration of gingko leaf extract, used to formulate supplements for mental performance and circulatory issues among other things, have been reported since 2003, when a group of researchers observed uncharacteristically high amounts of the flavonoid rutin in a sample of bulk material.

A disservice to the public

“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.”

Sales of ginkgo dietary supplements in the natural channel was estimated at $4.5 million in the US in 2016, according to data from SPINS. It’s estimated at $12.9 million that same year in the mainstream and multi-outlet channel.

“However, the ginkgo products that ​[consumers] are buying, if they are adulterated, may not be adequate to perform as well as those ginkgo extracts shown effective in the clinical research,” ​Blumenthal added. “As in many cases of adulteration and fraud, this creates a disservice to the public.”

Increased awareness on popular adulteration methods

According to Gafner, scientific literature assessing adulteration of ginkgo leaf extract suggests that adulteration is 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.”

Gafner noted that the assessment often depends on what the authors of a study have set as the parameters for adulterated products.

“Specifically, some authors may consider the occurrence of somewhat higher concentrations of quercetin or kaempferol acceptable, possibly due in part to the differences in the manufacturing process, while others may consider such deviations from the profile of authentic ginkgo leaf extract as adulteration.”

Despite the variety of parameters, “generally, the data suggest that the problems with ginkgo leaf extract adulteration have worsened over the years, though,”​ he added.

“I believe that the awareness of the ginkgo adulteration problem has increased, and that many responsible suppliers have adapted their analytical testing protocols to detect adulterated materials. But it has become difficult for those suppliers that offer authentic ginkgo leaf extracts to stay competitive since adulterated materials can be sold at a considerably lower price.”

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