Ginkgo biloba

Ginkgo leaf extract is one of the best-selling botanicals for memory and circulation. The largest and longest prevention trials did not show that it prevents dementia, and evidence in other uses is mixed. It is worth knowing that its main practical risks relate to bleeding and to seizures.

Standardised extracts are usually adjusted to flavone glycosides and terpene lactones and limited in ginkgolic acids, which are allergenic and cytotoxic. Teas and unstandardised preparations differ from the extracts used in research.

Proposed effects include improved blood flow, antioxidant activity and platelet-activating factor inhibition.

Two large prevention trials in older adults found no reduction in dementia over several years. Trials of standardised extract in people who already have dementia report small and inconsistent benefits. For claudication and tinnitus, benefits are marginal or absent.

Laboratory and animal work describes antioxidant effects, neuroprotection in ischaemia models and platelet-activating factor antagonism.

Evidence gap: Non-human evidence. It does not offset the negative findings of large human prevention trials.

Ginkgo may add to the effects of blood thinners and should be stopped before surgery on clinical advice. It may lower the seizure threshold and interacts with several medicines.

Common effects are headache, dizziness, stomach upset and allergic skin reactions. Serious reports include bleeding, including intracranial bleeding in isolated cases, and seizures in people with epilepsy or taking drugs that lower the seizure threshold. Stop before surgery on clinical advice. Avoid in pregnancy and breastfeeding, and avoid raw or roasted ginkgo seeds entirely, which are toxic and have caused seizures in children. People on anticoagulants or with bleeding disorders should not start it without clinician input.

Standardised leaf extract in capsules or tablets is the researched form; trials typically ran for several months.

For cognitive concerns, assessment for reversible causes, cardiovascular risk management, hearing and vision correction, physical activity, social engagement and treatment of depression are better-supported approaches. Ginkgo does not replace diagnostic evaluation of memory problems.

Educational example: an older adult on aspirin takes ginkgo for memory, has a fall, and bruising and bleeding are more extensive than expected; the supplement was not on the medication list. Decision factors are antiplatelet use, fall risk, surgery planning and epilepsy history. Questions to ask: does this add to my bleeding risk, should I stop before my procedure, and is there evidence it helps my situation? Marketing memory benefits to older adults despite large negative prevention trials is a clear example of claims outrunning evidence.