What is Ginkgo Biloba?
Ginkgos are very large trees, normally reaching a height of 66-115 feet, with some specimens in China being over 50 m (164 feet). Extracts are usually taken from the ginkgo leaf and are used to make tablets, capsules, or teas.
Why would Ginkgo be good for my brain?
Extracts of Ginkgo leaves contain flavonoid glycosides. Flavonoids are most commonly known for their antioxidant activity. An antioxidant is a molecule that can slow down or prevent the oxidation of other molecules. Oxidation is a chemical reaction that can produce free radicals, which start chain reactions that damage cells. Oxidative stress may accelerate Alzheimer’s Disease pathology. Thus taking antoxidants may have a beneficial effect of Alzheimer’s incidence.
Recent studies suggest that Gingko may not work
Ginkgo has many alleged properties but it is bought as a memory and concentration enhancer. However, studies differ about its efficacy.
Small studies for memory enhancement have had promising results. However a larger study published in 2002 by Solomon and colleagues showed that for adults with healthy cognitive function Ginkgo provided no measurable benefit in memory or related cognitive functions. This study was sponsored by the National Institute on Aging and included more than 200 healthy adults over age 60.
Recently the largest and longest independent clinical trial to assess Ginkgo biloba’s ability to prevent memory loss has found that the supplement does not prevent or delay dementia or Alzheimer’s disease. This study was published in November 2008 by DeKosky and colleagues. It was funded by the NCCAM (National Center for Complementary and Alternative Medicine), one of the National Institutes of Health.
The study, known as the Ginkgo Evaluation of Memory study, was a randomized trial in 5 academic medical centers in the United States that included more than 3000 volunteers aged 75 years or older with normal cognition. Participants received either the well-characterized ginkgo product, EGb-761, or a placebo. Participants were followed for an average of 6 years.
Results showed that Ginkgo Biloba at 120 mg twice a day was not effective in reducing the overall incidence rate of dementia. During the intervention period, 523 participants were diagnosed with dementia, 246 (16.1%) in the placebo group and 277 (17.9%) in the G. biloba group.
Current evidence suggests that Ginkgo is not effective in protecting the brain against cognitive decline. DeKosky and colleagues acknowledge that one possible shortcomings of their study is that an effect (positive or negative) of G. biloba may take many more years to appear… Other large trials are currently underway.
- Solomon, P. R, Adams, F., Silver, A., Zimmer, J., & DeVeaux, R. (2002). Ginkgo for memory enhancement: A randomized controlled trial. JAMA, 288(7), 835-40.
- DeKosky, S. T., et al. (2008). Ginkgo biloba for prevention of dementia: A randomized controlled trial. JAMA, 300, 2253-2262.