Study finds new truth about Gingko

Researchers conclude anti-oxidant does not prevent dementia, despite previously held beliefs

An eight-year series of trials conducted nationwide by a team that included University researchers has debunked the popular belief that ginkgo biloba can prevent dementia or improve cognitive function in older adults.

Ginkgo biloba is a flavanoid, an anti-oxidant substance that has anti-inflammatory properties, said Lewis Kuller, a professor of epidemiology at the University of Pittsburgh who helped conduct the trial. In the United States, people have been taking ginkgo biloba not only because they thought it might prevent dementia but also because they believed it to guard against vascular disease, he said.

"Here's a very inexpensive substance that basically is purchased over the counter," Kuller said. "Does it really have any benefit in preventing dementia and vascular disease?"

The research team conducted trials from 2000 to 2008. Research took place at six sites around the country: the University of Pittsburgh, Wake Forest University, the University of California at Davis, the University of Washington, Johns Hopkins University and the University of Vermont, Medical School Dean Steven DeKosky said. Exactly 3,069 people participated and were randomly assigned to treatment on either drugs or placebos, he said.

"We did the trial exactly the way you would do it if you wanted it to be approved by the [Food and Drug Administration]," DeKosky said, noting that drug companies follow this process to show their product is efficacious and safe before applying for FDA approval.

The results showed that ginkgo biloba has no effect on preventing dementia or cognitive decline, though it did have a positive effect in preventing lower extremity peripheral vascular disease in a small number of cases, Kuller said.

DeKosky said the results were "disappointing but useful to know." Americans spend $107 million on ginkgo products, he said, but he expects these numbers to decline based on the trial results.\n"There's always a lot of hope that something [will] come along," Kuller said in reference to alternative therapies in general. "Dementia's a very unpleasant disease. We don't have any treatment for it."

Kuller said he expects that some people will continue to take ginkgo biloba and believe in its effects but that others will move on to different alternative treatments.

"There's always a flavanoid of the year," he said, noting that people develop a belief system around these products even without seeing any "solid substantial evidence."

The trial also proved to be significant because it is the first study in which researchers started the work, recruited new people and finished the experiment, DeKosky said. In other projects, researchers either continued work on an existing group of subjects or had to stop trials because of negative side effects, he said.

Through the ginkgo biloba trial, researchers have learned much about how to study alternative therapies, DeKosky added.

"One of the things this study shows is how important it is to do these trials in a careful way," he said.

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