Gingko Biloba Does Not Prevent Dementia or Alzheimer's Disease: New Research
Gingko biloba, one of the most popular herbs taken in the USA and in Europe, has been shown to have no effect in reducing the rate of dementia or Alzheimer's disease, according to research published in the November 19 issue of JAMA.
Three thousand and sixty nine people over the age of 75 years with normal (n=2,587), or mild cognitive impairment (MCI;n=482), took part in the study. They were assessed every 6 months for an average 6.1 years for signs of dementia. 1545 of the participants were given a twice daily dose of 120mg extract of Ginkgo biloba and 1,524 were given a placebo.
Over the course of the study, conducted in five academic medical centers in the United States, 523 people developed dementia (246 from the placebo group and 277 from the group taking Gingko biloba). Ninety two percent of people diagnosed were classified as, ‘possible or probable Alzheimer's disease or Alzheimer's disease with evidence of vascular disease of the brain'. The rates of dementia or Alzheimer's did not differ between people taking Gingko and those who did not. No serious side effects were experienced by either participant group.
The findings are disappointing. Ginkgo biloba, extracted from leaves of the ginkgo biloba tree, has for a long time been promoted as improving brain function. Various studies have claimed ginkgo biloba has antioxidant and anti-inflammatory properties. Ginkgo biloba is also thought to increase cerebral circulation (blood flow to the brain). There is some evidence that ginkgo inhibits the formation of beta-amyloid, a protein that forms amyloid plaques in the brains of people with Alzheimer's disease
Previous studies have shown some small positive effects on people with Alzheimer's disease, whilst other studies show no effects.
Ginkgo biloba is not without side effects, some of them serious, but this may be due to dosage. Ginkgo is known to cause blood clotting problems and can have an adverse reaction to anesthesia. There are also problems with standardizing the amounts of active ingredients in herbal remedies. These can vary considerably between the various gingko products from different outlets.