Ginkgo Biloba: Benefits, Dosage, and Safety

What ginkgo biloba is

Ginkgo biloba is one of the oldest living tree species, often called a living fossil. The supplement is made mainly from an extract of the ginkgo leaf, which is the most commonly used form today. Ginkgo is a botanical, not an essential nutrient, so the body does not require it and there is no dietary requirement for it. Leaf extracts are typically standardized to flavonoid and terpene lactone content; the most studied standardized preparation in research is EGb 761. Ginkgo is not a vitamin or mineral, so no Dietary Reference Intake (RDA, AI, or UL) has been established by the NIH or NASEM.

What it does

• Provides plant compounds (flavonoids and terpene lactones) that are marketed for cognitive support, though NIH notes their effect on cognition in healthy people is uncertain
• Marketed as a dietary supplement for memory and thinking, but research has not established a benefit
• Used historically in traditional practice for circulation-related complaints, without conclusive modern evidence of benefit

Intake and dosing

Ginkgo Biloba is not an essential nutrient, so no Recommended Dietary Allowance or Tolerable Upper Intake Level has been set. Doses in studies vary widely. Because supplement doses are not standardised, discuss an appropriate amount with a clinician or pharmacist.

Deficiency and who is at risk

Not applicable. Ginkgo biloba is a botanical, not an essential nutrient, so there is no deficiency state and no dietary requirement. The body does not need ginkgo for any physiological function.

Who may need more

• No one requires ginkgo biloba, because it is not an essential nutrient and NIH has not shown it to be effective for any condition
• People considering it for memory or cognitive support should know that NIH research (including a trial of more than 3,000 people age 75 or older over a median of about 6 years) found no reduction in dementia rates versus placebo

Food sources

Ginkgo is not a dietary nutrient found across common foods. The plant sources are the ginkgo tree leaf (used to make extracts) and the seed. Fresh ginkgo seeds are toxic when consumed orally, and roasted seeds or crude plant material have caused serious side effects, so ginkgo is obtained as a manufactured supplement rather than as food.

Forms and absorption

Ginkgo leaf, usually taken as a leaf extract, is the most commonly used form and is sold as capsules, tablets, liquid extracts, and teas. Research on cognition has most often used standardized leaf extracts such as EGb 761, which are standardized to a set percentage of flavonol glycosides and terpene lactones. Ginkgo seeds are a distinct part of the plant and are not the supplement form; fresh seeds are toxic when eaten.

Safety, excess and interactions

Too much

The most common side effects reported are dizziness, gastrointestinal symptoms, and headache. Fresh ginkgo seeds are toxic when consumed orally, and serious side effects have also occurred in people who consumed roasted ginkgo seeds or the crude ginkgo plant. Ginkgo may increase the risk of bleeding, which is a particular concern for people taking anticoagulant drugs. Because ginkgo is a botanical rather than a nutrient, there is no tolerable upper intake level, but higher intake does not confer proven benefit and raises the chance of adverse effects.

Interactions to know

• Anticoagulant and antiplatelet drugs, such as warfarin: ginkgo may increase the risk of bleeding in people taking these medicines
• Ginkgo may also interact with other drugs; NCCIH advises consulting a health care provider before combining ginkgo with any medication

How status is measured

Not routinely measured. There is no clinical laboratory marker of ginkgo status because ginkgo is not an essential nutrient and the body maintains no store or requirement for it.

Regulated by the FDA as a dietary supplement under DSHEA, not as a drug. It is not FDA-approved to diagnose, treat, cure, or prevent any disease, and supplement products are not reviewed by the FDA for safety and effectiveness before marketing.

What the evidence supports

We grade the strength of evidence behind each common reason people take ginkgo biloba, mirroring how the NIH describes it.