Ginkgo biloba doesn’t prevent dementia or cognitive decline in older people, and doesn’t help boost memory in younger folks either, according to the best independent studies.

If you want to take it anyway, here’s something to consider: Chances are, the ginkgo you think you’re buying isn’t the ginkgo you get.

Adulterated content

“Consumers would find it disappointing that the ‘ginkgo’ in so many supplements isn’t 100 percent ginkgo,” notes Stefan Gafner, chief science officer at the American Botanical Council.

But industry insiders aren’t surprised.

In 1999, when first started testing ginkgo supplements, there was something fishy about the ginkgo in a quarter of the 30 brands that it sampled. In its 2003 testing, seven of nine ginkgo products flunked. In 2008, it was five of seven. And this year, it was six out of 10.

What’s going on?

“To reduce their costs, some manufacturers (or their ingredient suppliers) provide less ginkgo than claimed or use material that has been adulterated or ‘spiked’ with one or more compounds or extracts from other plants that can trick simple chemical tests,” notes ConsumerLab, which uses more sophisticated tests.

“This makes a product with little or no real ginkgo appear to be the real thing. In fact, it is now believed that ginkgo is among the most adulterated herbs on the market.”

(Which brands passed this year’s test? That information is available only to ConsumerLab’s subscribers.)

Others have found similar problems. In a 2012 study, seven of 18 ginkgo supplements purchased in suburban Washington, DC, or online “were clearly adulterated,” notes Gafner.1

And in a 2016 survey organized by the BBC, 33 of 35 ginkgo supplements purchased in London or online were adulterated. One contained no ginkgo at all.2

Doctor's Best Ginkgo
Ginkgo...or ginkno? There’s no way for shoppers to tell.

Money, money, money

“Industry experts agree that the adulteration of ginkgo extracts is intentional,” says Gafner.

(The pro-herb, nonprofit American Botanical Council is part of a consortium that is pushing supplement makers to clean up their act.)

Real ginkgo extract is expensive. It takes roughly 50 pounds of dried leaves to make one pound of extract.

“Most of the products contain some ginkgo,” notes Gafner. But some companies add cheaper compounds—they can cost as little as one-twentieth what ginkgo costs—that not all lab tests can pick up as frauds.

“Consumers think dietary supplements are supposed to be inexpensive,“ says Gafner. “Price pressure definitely has something to do with manufacturers cutting corners. That’s unacceptable.”

Ginkgo with benefits?

The evidence that ginkgo can protect your brain is anything but compelling.

In a 2008 study funded in part by the National Institutes of Health (NIH), researchers gave 3,069 men and women aged 75 and older 240 milligrams of ginkgo or a placebo every day. (They made sure the supplements had the right amount of ginkgo.) Over the next six years, the ginkgo takers were just as likely as the placebo takers to be diagnosed with dementia.3

And among those in the study who didn’t develop dementia, ginkgo was no better at slowing declines in memory, attention, use of language, or executive function (planning and organizing).4

Trials of ginkgo on memory, attention, and executive function in younger people have also come up empty.5

Some people with intermittent claudication—aches and cramps caused by poor circulation in the legs—claim that ginkgo relieves the pain of walking. But a Cochrane Collaboration review of 11 clinical trials found nothing much.6

No harm, no foul? Not exactly. “If you’re older, have a known bleeding risk, or are pregnant you should be cautious about ginkgo possibly increasing your risk of bleeding,” notes the NIH.


1J. AOAC Int. 95: 1579, 2012.
2Journal of Herbal Medicine 6: 79, 2016.
3JAMA 300: 2253, 2008.
4JAMA 302: 2663, 2009.
5Hum. Psychopharmacol. 27: 527, 2012.
6Cochrane Database Syst. Rev. 6: CD006888, 2013.

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