Sources: Ginkgo products come from the leaves of the only surviving member of the ginkgo family, a living fossil more than 200 million years old. Most commercial leaf production is from plantations in South Carolina, France, and China.

Traditional Use: Ginkgo leaf is a relatively new herbal medicine, used in China only since the fifteenth century. The leaves have traditionally been used for "benefitting the brain" and treating lung disorders, cough and asthma symptoms, and diarrhea. The leaf tea is applied externally to treat sores and remove freckles.

Current Use: Ginkgo is among the best-selling herbal medicines in Europe. Most research has focused on use of ginkgo to increase circulation to the extremities as well as the brain, especially in the elderly. Clinical use is supported by more than 400 scientific studies conducted since the late 1950s. Ginkgo extract has also been studied for the treatment of ringing in the ears (tinnitus), male impotence, degenerative nerve conditions such as multiple sclerosis, and other diseases. Ginkgo has demonstrated the potential to improve short-term memory, attention span, and mood in the early stages of Alzheimer disease by improving oxygen metabolism in the brain. The vast majority of studies have involved an extract called EGb-761. A 1996 controlled study looked at the effect of a ginkgo-leaf extract in the treatment of outpatients with dementia associated with Alzheimer. Twenty-eight percent of patients in the treatment group responded positively to the ginkgo leaf extract, compared with 10 percent in the placebo group. The first large-scale American clinical study on ginkgo was published in 1997 in the Journal of the American Medical Association. Focusing on ginkgo's effect on improving the short-term memory of early diagnosed Alzheimer disease, the researchers concluded that the herb is safe and stabilizing, and that, in a significant number of patients, it improves cognitive performance and social functioning. Ginkgo's effects have been attributed to flavone glycosides and ginkgolides, unique compounds that inhibit platelet-activating factor involved in the development of inflammatory, cardiovascular, and respiratory disorders. Ginkgolides' activity helps explain the herb's broad-spectrum biological effects. One reason for this conclusion is ginkgo's strong antioxidant activity. By "scavenging" free radicals, ginkgo directs antioxidant effects to the brain, central nervous system, and cardiovascular system. This mechanism makes it promising in the treatment of age-related declines of brain function.

References

DeFeudis, E. V. 1991. Ginkgo biloba Extract (EGb 761): Pharmacological Activities and Clinical Applications. Amsterdam: Elsevier.

Foster, S. 1996. "Ginkgo biloba." Botanical Series no. 304. Austin: American Botanical Council.

Funfgeld, E. W. (Ed.). 1988. Rokan (Ginkgo biloba), Recent Results in Pharmacology and Clinic. Berlin: Springer-Verlag.

Kanowski, S. et al. 1996. "Proof of Efficacy of the Ginkgo biloba Special Extract EGb 761 in Outpatients Suffering from Mild to Moderate Primary Degenerative Dementia of the Alzheimer Type or Multi-Infarct Dementia." Pharmacopsychiatry 29:47-56.

Kleijnen, J. and P Knipschild. 1992. "Ginkgo biloba for Cerebral Insufficiency." British Journal of Clinical Pharmacology 34:352-58.

Le Bars, P. L. et al. 1997. "A Placebo-Controlled, Double-Blind, Randomized Trial of an Extract of Ginkgo biloba for Dementia." Journal of the American Medical Association 278:1327-32.

Sohn, M. and R. Sikora. 1991. "Ginkgo biloba Extract in the Therapy of Erectile Dysfunction." Journal of Sex Education and Therapy 17:53-61.