Ginkgo biloba (also known as the maidenhair tree) is a deciduous tree native to China and cultivated widely throughout the southern and eastern United States. It may live up to 1,000 years, growing up to 120 feet in height and 4 feet in diameter. Its short, horizontal branches bear fan-shaped leaves measuring 5 to 10 centimeters in width. The tree bears an inedible, berry-like fruit with small edible seeds. Extracts from ginkgo leaves are used for health purposes.
The active components in ginkgo leaves include antioxidant compounds known as ginkgo flavone glycosides, and unique terpene lactone compounds called ginkgolides and bilobalides. Ginkgo biloba extracts are commonly standardized to concentrations of 24% flavone glycosides and 6% terpene lactones, and this concentration is used in mostmedical studies.
Most people take divided doses, totaling 120 to 160 mg per day, of an extract standardized to 24% flavone glycoside and 6% terpene lactone concentration. Clinical studies have used doses ranging from 40 to 300 mg per day. Ginkgo is safe and generally well tolerated, with a very low occurrence of side effects. Stomach discomfort, headaches, and dizziness have been reported by a small percentage of users.