Presumed herbal brain booster fails to show any benefit in largest, longest trial ever conducted; prior studies provided enough positive evidence to warrant more research
by Craig Weatherby
The leaves of the maidenhair tree, Ginkgo biloba, have been used medicinally in China for thousands of years.
Brain health was among ginkgo’s most common uses, which led to hopes that concentrated extracts of the herb might help deter mental decline.
Millions of Americans take ginkgo pills because they’ve read that it can boost memory, fight off age-related mental fog, and even reduce the risk of dementia disorders… including Alzheimer’s disease.
We cannot yet be certain that ginkgo works as advertised (or implied), given the mixed results from the limited clinical studies conducted to date.
But positive results from some clinical trials have kept consumers buying and provided sufficient evidence to keep researchers interested.
Evidence has been mixed but encouraging
Here’s how the authors of a rigorous evidence review characterized the evidence for ginkgo's brain-boosting powers eight years ago:
“Overall there is promising evidence of improvement in cognition and function associated with Ginkgo” (Birks J et al. 2002).
However, they stressed that the positive ginkgo trials available then were generally small, imperfectly designed, and lacked enough statistical heft to provide proof.
Little had changed when the same evidence-reviewers published a somewhat less hopeful update last year:
“The evidence that Ginkgo biloba has predictable and clinically significant benefit for people with dementia or cognitive impairment is inconsistent and unreliable” (Birks J et al. 2009).
And until last week, the need they identified in 2002—for larger, better-controlled clinical trials—remained unmet.
As if to answer their plea, the Journal of the American Medical Association just published the results of the largest, best-designed clinical trial conducted to date (Snitz BE et al. 2009).
Unfortunately, the outcome was negative, with ginkgo supplements performing no better than placebo pills.
Details of the new ginkgo trial
A team from the University of Pittsburgh recruited 3,069 people between 72 and 96 years of age, with the average age being 79 (Snitz BE et al. 2009).
The participants were randomly assigned to receive either ginkgo pills or placebo pills for an average period of 6.1 years.
The ginkgo group took 120mg of a common extract (EGb 761) made by Germany’s Schwabe Pharmaceuticals.
Their decision to use Schwabe’s EGb 761 ginkgo extract made sense for three reasons:
After six years, the ginkgo group did no better than the placebo group on tests of mental performance, including memory, attention, language, and so-called “executive” (decision-making) brain functions.
- EGb 761 is used in many ginkgo supplements.
- Most non-EGb 761 ginkgo extracts mimic its chemical profile.
- EGb 761 is the most widely studied ginkgo extract and the one that has shown the most promise in prior trials.
As the Pittsburgh group wrote, “In sum, we find no evidence that Ginkgo biloba slows the rate of cognitive decline in older adults” (Snitz BE et al. 2009).
Still, given the large body of previously published positive evidence, the new study should not be viewed as proving ginkgo does nothing to boost aging brains.
But the evidence collected to date suggests that one can’t rely on ginkgo alone to forestall brain aging.
Instead, it makes sense to ensure adequate mental and physical exercise, as well as ample intake of all nutrients, foods, and herbs associated with brain health, including fish-derived omega-3s, curcumin (from turmeric), huperzine-A (from a Chinese medicinal moss), and berries.
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