One of the most popular herbal supplements is ginkgo biloba. It has been claimed that it enhances memory, improves mental function and prevents or slows the progression of dementia. There is limited scientific evidence showing that?ginkgo supplements may modestly slow the progression of dementia associated with vascular disease or Alzheimer?s disease.1 However, there have been no carefully controlled trials to support claims that?ginkgo supplements enhance mental function or improve memory in healthy older people. This lack of good scientific evidence has not prevented sellers of?ginkgo supplements from claiming their products do enhance memory in healthy people. The manufacturer of Ginkoba? claims that benefits will occur within ?at least 4 weeks of uninterrupted use.?2
A recent large clinical trial of more than 230 reasonably healthy people, age 60 years or older, examined the impact of Ginkoba supplied by the largest manufacturer and distributor of gingko supplements. Subjects were randomly assigned to take either the Ginkoba or a look-a-like placebo. Cognitive function tests were administered before starting the supplement and again at the end of six weeks. The results of this study did not support the manufacturer?s claims that?ginkgo supplements improve memory. There was no improvement on any of the 14 standard neuropsychological tests. In addition, self-reports of changes in memory or other measures of cognitive function and also observations made by a family member or friend found no difference between the placebo and the Ginkoba groups.3Bottom Line: The results of this study make it clear that?ginkgo supplements are ineffective for enhancing mental function and improving memory in most older people. While?ginkgo supplements are not particularly dangerous, they can increase bleeding and may cause stomach problems and headaches in some people.4 Because?ginkgo supplements can have adverse effects, it seems reasonable to recommend that older people not use these supplements. More research needs to be done to establish whether or not?ginkgo supplements have any benefits for treating and/or preventing Alzheimer?s disease and vascular dementia. In the meantime the best advice for otherwise healthy people is to forget their ginkgo.By Dr. James J. Kenney, PhD, RD, FACN1. JAMA 1997;278:1327-322. www.ginkoba.com3. JAMA 2002;288:835-404. Am Fam Physician. 1999;59:1239-44
Update: a Toxicology report from The National Toxicology Program found that Ginkgo Biloba extract caused cancer. Dr. Kenney concludes, the benefits were not proven and now there is an additional potential risk added to the equation. Here is the toxicology report:
http://ntp.niehs.nih.gov/ntp/htdocs/LT_rpts/TR578_508.pdf