Ginkgo biloba a bust in preventing Alzheimer’s disease or other dementias, study says

Much like some other antioxidants, the promise of ginkgo biloba has fizzled recently after being tested in a large clinical trial. The Ginkgo Evaluation of Memory (GEM) Study, published in the November 19, 2008 issue of the Journal of the American Medical Association (JAMA) followed more than 3,000 people aged 75 or older for roughly six years—making it the largest ginkgo-dementia trial yet—and found ginkgo biloba did not decrease incidents of Alzheimer's disease or other forms of dementia in people with normal cognition, or those with mild cognitive impairment.

Ginkgo is extracted from the leaves of the Chinese maidenhair tree, and its seeds have been used in herbal medicines for thousands of years. The supplement is available in pills and teas and is commonly used to help prevent Alzheimer's disease, and other forms of dementia, as well as to possibly improve blood flow and brainpower.

Ginkgo supplements often promote that last attribute by touting memory enhancement and improved mental focus, but recent studies place those claims in doubt. A 2007 study, published in the Journal of the American Dietetic Association, did not support improved mental function or quality of life in older people with normal cognition. And a 2002 study published in JAMA, found that ginkgo biloba offered no measurable benefit to memory or related cognitive function in elderly subjects when taken according to manufacturer's instructions.

The authors of the GEM study note that it's possible potential benefits from ginkgo biloba supplementation may take many more years to manifest. That's because the neurological changes associated with dementia take place over a long period of time. And indeed, all of the studies we looked at used older subjects. But in an editorial accompanying the GEM study, Lon S. Schneider, M.D, of the Keck School of Medicine at the University of Southern California, concludes, "Users of this extract should not expect it to be helpful."

It seems that counting on ginkgo biloba for any cognitive benefits might amount to a leap of faith, and one that is not without cost. Americans spent about $107 million on ginkgo biloba supplements in 2007, according to the Nutrition Business Journal. And a year's supply can cost about $200 per person. But until there is more convincing evidence of efficacy, you may be better off saving that money instead.

And, while ginkgo is widely considered safe, there is some concern about increased risk of bruising and bleeding, and potential drug interactions. If you're considering taking a natural medicine, it's always a good idea to talk it over with your doctor first.

—Kevin McCarthy, associate editor

For more, see our Natural Medicine Ratings and drug interactions for ginkgo biloba (subscribers only), and our Treatment Ratings for Alzheimer's disease and dementia (subscribers only). For those who have Alzheimer's disease, or have a loved one who does, see our free Best Buy Drug Report for treatment comparisons.