Ginkgo biloba, also known as the maidenhair tree, is one of the world’s oldest living tree species. Once widely distributed, this species was almost destroyed during the last Ice Age in all regions of the world except China, where it has been used in Traditional Chinese Medicine for several thousand years. Leaves of Ginkgo biloba are used to prepare an extract, the main active ingredients of which are chemical substances called flavone glycosides and terpene lactones. The composition of commercially available extracts of Ginkgo biloba may vary; extracts should be standardized to contain 24% flavone glycosides and 6% terpene lactones. Unprocessed leaves should not be used (e.g. in teas), as they contain chemicals (removed during processing) which can trigger allergic reactions.