Ginkgo may protect brain against stroke damage

A stroke occurs when blood flow to brain tissues is disrupted, killing brain cells by robbing them of oxygen and nutrients. The most likely cause is blockage of an artery in the neck or head. When a portion of the brain is damaged, patients are often left with some disability, such as paralysis, loss of speech or memory lapses. Because the brain damage from the stroke is mostly caused by oxidative stress, i.e., excess free radicals, researchers have long pondered whether antioxidants would help limiting the brain damage from a stroke.

Ginkgo biloba is a popular supplement. Ginkgo biloba extract is collected from the dried green leaves of the Ginkgo plant. Gingko biloba extract contains high levels of antioxidants including flavonoids and terpenoids,. The therapeutic properties of the ginkgo plant are said to include treatment for blood disorders and memory problems, enhancement of cardiovascular function and to improve eye health.

Researchers from Oregon Health Sciences University reported that ginkgo may reduce the extent of brain damage caused by stroke.  In an animal study, 60 mice were randomized into three treatment groups: low dose group was given 50 mg/kg of ginkgo biloba daily for 7 days; high dose group was given 100 mg/kg of ginkgo biloba daily for 7 days; and the placebo group. On day 7, a stroke was induced in mice. At 24 hours, the animals were evaluated and infarct volume (i.e. brain damage extent) was determined.

It was observed that the low dose group has an average of 14% of brain damage. In comparison, the placebo group and the high does group have similar amounts of brain damage of about 20%. In addition, the low dose group has an improved neurological function score than the other two groups.

The researcher concluded that oral ginkgo biloba therapy could produce significant reductions in stroke infarct volume. However, the beneficial effect appears to be dose related. Because ginkgo biloba has blood-thinning effect, it was recommended that the daily supplement dosage should not exceed 600mg for adults.

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Journal Reference: Wayne M. Clark; Lisa G. Rinker; Nikola S. Lessov; Stuart L. Lowery; Marilyn J. Cipolla, Efficacy of Antioxidant Therapies in Transient Focal Ischemia in Mice Stroke 2001; 32:1000-1004,