Ginkgo biloba is a tree whose leaf extract is one of the best-known herbal supplements. It is promoted for memory, dementia, anxiety, tinnitus and other conditions, but NCCIH says it has not been shown to work for any condition it has been studied for.
Also known as: ginkgo, ginkgo leaf extract, EGb 761.
Ginkgo has no intake value or upper limit. The GEM trial (DeKosky 2008) used 120 mg of ginkgo leaf extract twice a day for a median of 6.1 years. These are study protocols, not a recommendation.
It is sold in the US as a dietary supplement. Under the 1994 dietary supplement law (DSHEA), FDA does not approve dietary supplements before they are marketed, and the maker, not FDA, is responsible for safety and labeling.
NCCIH says there is no conclusive evidence that ginkgo helps any health condition. In the Ginkgo Evaluation of Memory (GEM) study (DeKosky 2008), 3,069 people aged 75 or older took 120 mg of ginkgo extract twice a day or placebo for a median of 6.1 years; ginkgo did not lower the rate of dementia or Alzheimer's disease, and it did not slow progression in people who started with mild cognitive impairment. NCCIH adds that ginkgo may have a modest benefit for dementia symptoms, but the evidence is inconsistent, and it is not helpful for preventing heart disease, treating high blood pressure, or tinnitus.
Safety, per NCCIH: leaf extracts are likely safe for most adults in moderate amounts and were used in studies lasting up to 6 years; the most common side effects are dizziness, stomach upset and headache. Fresh ginkgo seeds are toxic, and roasted seeds or the crude plant have caused serious side effects. Ginkgo may raise the risk of bleeding in people taking anticoagulants such as warfarin and may interact with other drugs. It may be unsafe in pregnancy, where it might cause early labor or extra bleeding during delivery.
We could not find a single published half-life or time to peak for ginkgo extract that applies to a supplement dose, so we do not list one. Extracts are mixtures of many plant compounds, so no single figure would describe them.
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