New study a blow to ginkgo's reputation

(CNN) -- Memory problems usually go hand-in-hand with wrinkles and body aches as we grow older. But if you're looking to the supplement ginkgo biloba to keep the mind in steel-trap form, a new study says it might be wiser to look elsewhere.

Researchers at Williams College in Williamstown, Massachusetts, gathered 230 people between the ages of 60 and 82 to help them test ginkgo's ability to improve memory and concentration as advertised. Half the group was given 40 milligrams of ginkgo three times per day for six weeks per the maker's recommendations. The others were given a placebo. Neither group was told what they were taking.

No difference in mental sharpness was seen by study participants or their companions. But the researchers took it a step further with a battery of tests. They looked at verbal and nonverbal learning and memory, attention and concentration.

Their conclusion? "When taken following the manufacturer's instructions, ginkgo provides no measurable benefit in memory or related cognitive function" in generally healthy adults, the researchers write in Tuesday's issue of the Journal of the American Medical Association.

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It's a blow to aging baby boomers and the elderly alike who fear loss of memory, independence and mind-ravaging diseases like Alzheimer's. Ginkgo has the added bonus of being promoted as all natural to a public that's funneling more and more money into alternative health care. Available over the counter in pill or drink form, ginkgo is consumer-friendly too.

But it's important to remember that ginkgo -- like other supplements -- is not governed by the Food and Drug Administration. There are also no standards for supplement makers to follow.

The herb is actually an extract from leaves of the ginkgo biloba tree. According to the National Institute on Aging, ginkgo has antioxidant properties like vitamins C and E. Antioxidants are thought to cleanse the body of damaging free radicals caused by aging, smoking and pollution among other things.

Molly Wagster, PhD, says there is a "biological plausibility" that gingko may improve cognitive function. However, "that certainly hasn't been well documented yet." Wagster is program director for the neuroscience and neuropsychology of aging program at the NIA.

The NIA is partially funding a five-year gingko study currently under way. That study uses double the herb's dosage -- 240 milligrams per day. Wagster says a higher dosage and/or longer duration may increase the likelihood of a positive outcome.

The herb is thought to improve blood flow to the brain which may account for its reputation as a memory enhancer. It's also believed to improve mood, reduce anxiety and stress, dizziness, ringing in the ears, and headache. Ginkgo has also been used to increase circulation to the limbs and in the treatment of asthma. Serious side effects are rare but ginkgo could affect blood clotting.

Although it's been used in China for centuries, the first ginkgo research was published in the United States just five years ago. In that study, researchers found a small improvement in people taking ginkgo.