Ginkgo

Ginkgo biloba is an ancient Chinese herbal medicine, now widely available in pill form, especially in many "brain booster" supplements. Ginkgo contains many chemicals--notably flavonoids and terpenoids, which together may improve blood flow, reduce blood clotting, and have anti-inflammatory, antioxidant, and neuro-protective effects.

Claims, purported benefits: Improves circulatory disorders; prevents or reduces memory problems and dementia; treats eye disease and tinnitus. Prescribed in France and Germany for years against vascular disease and "cerebral insufficiencies," which can mean anything from absentmindedness and confusion to dementia.

Evidence: Some studies have found limited benefits in people with mild to moderate Alzheimer's disease or other kinds of dementia. But most of the studies have been small, poorly designed, or otherwise flawed. And there’s no convincing evidence that ginkgo helps healthy older people with normal age-related memory problems. Ginkgo shows promise for treating circulatory disorders, such as intermittent claudication (pain in the legs due to obstructed blood flow). Other claims are unproven.

Bottom line: Many questions remain unanswered—how effective ginkgo is against one disorder or another, how long it should be used, what the proper dosage is. Commercially available ginkgo products may not contain the same preparations used in the studies—or much ginkgo at all; worse, some have been shown to be high in lead. There's no evidence that ginkgo is a "brain booster" for healthy people. And people with Alzheimer’s should not experiment with ginkgo without professional advice; drug treatments may be better. Because of its anti-clotting effects, ginkgo may increase the risk of bleeding, particularly if you take aspirin daily. Do not use ginkgo if you have a blood clotting disorder.