Ginkgo (Ginkgo biloba) is prepared from leaves of the ginkgo tree (commonly planted in the US for ornamental purposes). Active ingredients are believed to be terpene ginkgolides and flavonoids.
The fruit of the gingko tree, which is quite malodorous, is not used in ginkgo products. Contact with the fruit pulp, which may be present under female ginkgo trees, can cause severe skin inflammation (dermatitis). The raw seeds of the fruit are toxic and can cause seizures and, in large amounts, death. Cooked ginkgo seeds are eaten in Asia and are available in Asian food shops in the US; because the seeds do not contain ginkgolides and flavonoids, they do not have therapeutic effects.
Strong scientific evidence supports use of ginkgo for symptomatic relief of claudication, although exercise and cilostazol may be more effective. Gingko increases the distance that affected people can walk without pain.
Ginkgo has long been used in people with dementia. Benefit in dementia seems unlikely based on a recent large clinical trial in which ginkgo was not effective in reducing the development of dementia and Alzheimer's disease in older people. However, a previous large US clinical trial indicated that ginkgo temporarily stabilized mental and social function in people with mild to moderate dementia. Although data are conflicting, any real effect is likely to be modest.
Studies show gingko does not seem to alleviate memory loss, tinnitus, or altitude sickness. Gingko may prevent damage to the kidneys caused by the immunosuppressant cyclosporine.
Nausea, dyspepsia, headache, dizziness, and heart palpitations may occur. Ginkgo may interact with aspirin, other NSAIDs (see Pain: Nonopioid Analgesics), and warfarin and may reduce the efficacy of anticonvulsants.
Last full review/revision May 2009 by Ara DerMarderosian, PhD
Content last modified June 2010