Ginkgo (Ginkgo Biloba)

Medical Uses

Ginkgo is used for circulation problems, Alzheimer’s disease, difficulties with memory, ringing in the ears, headaches, and dizziness. Ginkgo biloba is licensed in Germany for treating: cerebral dysfunction with difficulties in memory, dizziness, tinnitus (ringing in the ears), headaches, emotional instability with anxiety, and intermittent claudication.

Historical Uses

Legend has it that Chinese monks saved the ginkgo tree from extinction by growing it in monastery gardens.

Growth

The ginkgo is the oldest known living tree in the world. It is not difficult to grow, and ginkgo trees can be found in many city areas in the United States, including Central Park in New York City. The trees are able to withstand pollution and disease. Their leaves turn yellow in the fall.

Ginkgo: Part Used

• Dried leaves

Major Chemical Compounds

• Diterpenes known as ginkgolides, sesquiterpene bilobalide, quercetin

Ginkgo: Clinical Uses

Ginkgo is used for peripheral vascular disease, such as intermittent claudication and cerebral insufficiency. It is approved by the German Commission E and the World Health Organization. Ginkgo biloba is licensed in Germany for treating cerebral dysfunction with difficulties in memory, dizziness, tinnitus, headaches, emotional instability with anxiety, and intermittent claudication. Its antistress effect makes ginkgo biloba useful in the treatment of Alzheimer’s disease. It helps to improve memory and may be useful in reducing symptoms of attention deficit hyperactivity disorder (ADHD).

Mechanism of Action

Diterpenes known as ginkgolides combine with a sesquiterpene bilobalide in Ginkgo biloba extract to improve the tolerance of brain tissue to hypoxia and to increase cerebral circulation. Rutin-type flavones reduce capillary fragility, tend to prevent ischemic brain damage, and inhibit lipid peroxidation of cell membranes by inactivating free oxygen radicals. These effects combine to alleviate impaired cerebral circulation, particularly in elderly people, and relieve unpleasant associated symptoms, such as dizziness, depression, tinnitus, and short-term memory loss. Ginkgo biloba extract (Egb 761) helps in neurodegenerative disorders because of its antioxidant properties and enhances”neuronal plasticity”.

Ginkgo: Dosage

Standardized extract: For people over age 50, studies have used 120 to 240 mg daily in divided doses for 4 weeks to 9 months. It takes 4 to 6 weeks for positive effects to occur. The patient should be reviewed at 3 months. Standardized products used in studies include Schwabe Egb 761 extract, BioGinkgo, and Whole Foods Ginkgo. Extract of Ginkgo biloba used in studies and known as Egb is standardized to 24 percent flavone glycosides and 6 percent terpenes. In a review of the literature, Egb showed a higher rate of treatment response at 240 mg per day than at 120 mg per day without increasing side effects.

Side Effects

Ginkgo biloba may elevate the international normalized ratio. It also may cause mild gastrointestinal disturbances, allergic skin reactions, and headache. If headache occurs, the herb should be discontinued.

Contraindications

• None are known.

Herb-Drug Interactions

Ginkgo may interact with trazodone (Desyrel), causing CNS depression and coma (Natural Medicines, 2000). It may increase bleeding times when taken with aspirin or Coumadin. Also, it may potentiate the effects of papaverine in treating male impotence.

Pregnancy and Breast-Feeding

No restrictions are known.

Summary of Studies

Oken et al. (1998). This meta-analysis of 4 studies included 212 patients who used standardized extract (50:1), standardized to 6 percent terpene lactones and 24 percent ginkgo flavone gly-cosides. Products included Tebonin (Egb 761, Schwabe of Germany) and Kaveri (LI 1440, Lichtwer Pharma of Berlin and Pittsburgh). Results: 120 to 240 mg Ginkgo biloba leaf extract for 3 to 6 months had a small but significant effect on objective measures of cognitive function in Alzheimer’s disease without causing adverse effects.

Roncin et al. (1996). This placebo-controlled clinical trial included 44 mountain climbers, half of whom took 80 mg of standardized ginkgo extract twice daily; the others took a placebo. Results: Ginkgo was dramatically effective in preventing altitude sickness and was more effective than placebo in preventing cold-related circulation problems.

Le Bars et al. (1997). This placebo-controlled, double-blind, randomized trial included 202 subjects and lasted 52 weeks. The subjects used an extract of Ginkgo biloba (Schwabe’s Egb 761), known in the United States as Ginkoba or Ginkgold at a dosage of 40 mg t.i.d. before meals for dementia. Results: A slight improvement in outcomes with mild to moderate gastrointestinal symptoms.

Kanowski et al. (1996). This double-blind, placebo-controlled, randomized, 24-week study included 156 men and women with Alzheimer’s disease and multi-infarct dementia. They received Ginkgo biloba at a dosage of 120 mg b.i.d. Results: Improvement was noted in psychiatric tests and mild depressive symptoms compared to placebo.

Hofferberth (1994). This double-blind, placebo-controlled, 12-week study included 40 patients with Alzheimer’s disease who took 80 mg of ginkgo (Egb 761) or placebo t.i.d. Results: Memory and attention improved significantly after one month. Psychopafhology, psychomo-tor performance, functional dynamics, and neurophysiology improved as well. No side effects were noted.

Schubert & Halama (1993). This double-blind, placebo-controlled, randomized, 8-week study included 40 subjects ages 51 to 78 with resistant depression. These patients showed insufficient response to tricyclic and tetracyclic antidepressants for 3 months. Patients continued on their medications and also received either 80 mg of ginkgo t.i.d. or a placebo. Results: Improvement was noted in depressive symptoms after 4 weeks, with a highly significant improvement after 8 weeks and a significant improvement in cognitive function in the ginkgo group.

Stough et al. (2001). In a randomized, double-blind, placebo-controlled clinical trial of 61 subjects using Ginkgo biloba extract (Egb) over 30 days, resuslts showed a significant improvement in working memory.

Lyon et al. (2001).In an open study of 36 children with ADHD using AD-FX of CV Technologies (a combination herbal product containing American ginseng extract [Panax quinquefolium] 200 mg and Ginkgo biloba extract 50 mg), results showed improvement in symptoms after 2 and 4 weeks of treatment.

Zhang et al. (2000). Ginkgo biloba extract (Egb 761) was shown to help regulate hypertension and protect cerebral microcirculation in rats.

Wesnes et al. (2000). A double-blind, placebo-controlled, 14-week, parallel group multicenter trial of two dosing regimens of capsules containing standardized extracts of Ginkgo biloba (GK501) and Panax ginseng (G115) 100 mg in 256 healthy subjects showed that the combination extracts improved working and long-term memory in a 12-week period, including a 2-week washout period (2 weeks without taking the herb).

Ginkgo: Warnings

Ginkgo biloba may increase the risk of bleeding.

• It may cause mild stomach disturbances, allergic skin reactions, and headache. If you get a headache, stop taking the herb and consult your health-care practitioner.

• Don’t take Ginkgo biloba if you take trazodone (Desyrel), aspirin, a blood thinner, or papaverine.