The standardized ginkgo biloba extract is from the leaves of Ginkgo Biloba L., family Ginkgoaceae. The Ginkgo species has survived for over 200 million years, and some ginkgo trees live to be over 1,000 years old. Although the ginkgo tree is a very old one, the standardized extract prepared from its leaves is quite new, having been developed in the past 20 years. The standardized extract has much more popularity because the leaves cannot be used as extemporaneous herbal remedy such as tea due to an insufficient quantity of the principles. Today the standardized Ginkgo Biloba extract (24/6) made from ginkgo leaves are among the best-selling herbal medicinal products in the world and is a well established product in the United States. 

Therapeutic Use  

The Chinese, who have always recognized the tree's unique stamina and longevity, have used ginkgo nuts for thousands of years as a remedy for cancer, venereal disease, asthma, lung weakness and congestion, impaired hearing and to increase sexual energy and generally promote longevity. Today the ancient ginkgo has sparked renewed interest throughout the world because medical researchers have isolated chemical compounds from ginkgo that show startling effects in humans. These compounds regulate blood flow to the brain, legs and other extremities and control levels of various neurotransmitters in the brain, thus helping to counteract memory loss, depression and lack of alertness which may develop in old age. These same compounds also block a substance called platelet activating factor (PAF) which, by over-stimulating the immune system, may lead to conditions such as asthma, toxic shock from bacterial poisons and perhaps even atherosclerosis and stroke. The major therapeutic uses of ginkgo is in the following areas: 

Vascular Insufficiency. The primary therapeutic property of ginkgo is to increase the flow of blood into areas previously deprived of this life-giving substance to one degree or another, including the brain, the lower limbs, all arteries, veins, even the smallest capillaries. Decreased blood flow to the brain can adversely affect memory, concentration, intellectual ability, vision, equilibrium and balance. It may also lead to symptoms such as headaches, depression, mental confusion. Stroke can occur because of lack of blood flow and oxygen to brain tissue. Ginkgo is used to prevent and even treat all of these conditions. 

Hearing disorders. Ringing in the ears (tinnitus), disturbance of balance, dizziness (vertigo), sudden hearing loss and hearing weakness may all result from lack of proper blood circulation. These conditions can also be caused by free radical damage. These problems that has resulted from a disturbance in blood supply (and most such problems have a vascular component) can be beneficially affected by the ingestion of Ginkgo Biloba extract. 

Free Radical Inhibition. Researches and empirical data suggest that free radicals are inherently involved in the aging process and in degenerative diseases such as cancer, diabetes, blindness, atheroscleriosis and so forth. Free radicals are generated by the natural metabolic processes of the body. In recent years, in many experimental trials ginkgo biloba extract has shown considerable ability to act as an oxygen scavenger and directly prevent the occurrence of free radical damage. The presence of very potent flavonoids in the extract is primarily responsible for plant high degree of anti-oxidant activity. 

Scientific Understanding of the ginkgo extract 

Although complete analysis of Ginkgo Biloba Extract have not been conducted, laboratory studies have found that an extract of ginkgo contain a number of flavonol and flavonol glycosides. The extract also contain a group of unique, closely related, bitter, 20-carbon diterpene lactone derivatives known as Ginkgolides A, B, C and M. In addition, a similar 15-carbon sesquiterpene designated bilobalide is also present together with 6-hydroxykynurenic acid, shikimic acid, protocatechuic acid, vanillic acid, and p-hydroxybenzoic acid. 

Standardized extract with minimum ginkgo flavonol glycosides 24% and ginkgo terpene lactones 6% is the major product used for many clinical studies. The data from these studies showed the ginkgo extract at above concentration is effective. These studies also showed that therapeutic effects of ginkgo biloba extract are attributed to a mixture of these constituents, not to a single chemical entity. 

Dosage and Toxicity 

The suggest dosage of the standardized ginkgo biloba extract (24/6) is 120 to 160 mg per day. Ginkgo biloba extract is sold in the United States as a food supplement, usually in the form of tablets containing 40 mg of the extract. Recommended dosage is 1 tablet 3 times daily with meals. 

Before ginkgo biloba was ever approved for human consumption it had been extensively tested for potential side effects. Virtually none were found. One long term study was carried out to determine if very large doses of ginkgo biloba extract had any influence on delicate endocrine balances. The results of all hormonal and blood assays were negative.