Ginkgo (Ginkgo biloba) is one of the oldest living tree species. Most ginkgo products are made with extract prepared from its fan-shaped leaves. The most helpful components of ginkgo are believed to be flavonoids, which have powerful antioxidant qualities, and terpenoids, which help improve circulation by dilating blood vessels and reducing the "stickiness" of platelets. Ginkgo is commonly available as an oral tablet, extract, capsule or tea. Don't eat raw or roasted ginkgo seeds, which can be poisonous. Most research on ginkgo focuses on its effect on dementia, memory and pain caused by too little blood flow (claudication).