Ginkgo is derived from the leaves of the ginkgo tree (commonly planted for ornamental purposes). The leaves contain numerous biologically active substances, such as ginkgolides and flavonoids. Ginkgo is one of the most commonly used herbal supplements.
The fruit of the ginkgo tree is not used in ginkgo products because of its bad smell. Contact with the fruit pulp, which may be encountered under female ginkgo trees, can cause severe skin inflammation (dermatitis). The seeds of the fruit are toxic and can cause seizures and, in large amounts, death.
(See also Overview of Dietary Supplements.)
Ginkgo reduces the clotting tendency of particles in the blood that help stop bleeding (platelets), dilates blood vessels (thereby improving blood flow), and reduces inflammation. People take ginkgo for many reasons, such as improving blood flow to the lower legs in people with atherosclerotic vascular disease of the arteries in the legs (peripheral arterial disease) and treating dementia (as in Alzheimer disease). Scientific studies show ginkgo benefits people with peripheral arterial disease, although the benefit is minor. Ginkgo increased the distance that affected people could walk without pain. Major benefits for people with dementia seems unlikely based on findings from a large clinical trial. In this clinical trial, ginkgo was not effective in reducing the development of dementia and Alzheimer disease in older people. However, other studies indicate that ginkgo, when taken at sufficient doses and for more than 5 months, can temporarily stabilized mental and social function in people with mild to moderate dementia.
Studies show ginkgo may help to slow age-related macular degeneration, which is an eye disease. Earlier evidence showed ginkgo helped relieve ringing in the ears (tinnitus) but more recent information indicates it does not help people whose main problem is tinnitus. Ginkgo may prevent altitude sickness in some people. Ginkgo may prevent damage to the kidneys caused by the drug cyclosporine, which suppresses the immune system.
Emerging evidence reports the benefit of ginkgo in treatment of type 2 diabetes. When combined with metformin, ginkgo significantly decreased fasting glucose and HbA1c.
Ginkgo may interact with drugs that prevent blood clots, aspirin, and other nonsteroidal anti-inflammatory drugs (NSAIDs). Ginkgo may also reduce the effectiveness of antiseizure drugs.
The following is an English-language resource that may be useful. Please note that THE MANUAL is not responsible for the content of this resource.
National Institutes of Health (NIH), National Center for Complementary and Integrative Health: General information on the use of ginkgo as a dietary supplement