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Ginkgo biloba

The classic “memory herb” — and one of the few supplements tested in a trial big enough to actually settle the question. It did not pass.

Reviewed by Bodil Isaksson, Licensed Biomedical Scientist (Sweden)Last reviewed July 2026Supplement guide

SupplementsBrain & cognitionMyth-check

Ginkgo has been sold for “memory and circulation” for decades, and for years the evidence was a muddle of small, short, mixed trials — enough ambiguity to keep the marketing alive. Then two large, long, well-run trials asked the direct question, and the answer came back clearly. If you want to know whether ginkgo keeps your mind sharp or wards off dementia, we no longer have to guess.

Key takeaways

  • The GEM study — over 3,000 older adults, 240 mg/day, followed ~6 years — found ginkgo did not reduce dementia or Alzheimer’s incidence.1
  • The same cohort showed no slowing of normal cognitive decline either.2
  • Small acute-cognition effects in healthy people are inconsistent and, at best, trivial.
  • Real caution: ginkgo has antiplatelet activity and can raise bleeding risk with anticoagulants, aspirin or surgery.3

The verdict, up front

We usually build up to a conclusion; here it belongs at the top. For its headline claims — preventing dementia and preserving memory as you age — ginkgo does not work. That is not a cautious “evidence is limited” hedge; it is the result of trials specifically designed and powered to detect a benefit, which found none. If someone is taking ginkgo to protect their brain, they are spending money on a false promise.

What the big trials found

The Ginkgo Evaluation of Memory (GEM) study randomized more than 3,000 people aged 75+ to a standardised extract (EGb 761) at 240 mg/day or placebo and followed them for roughly six years. Ginkgo produced no reduction in the rate of all-cause dementia or Alzheimer’s disease.1 A companion analysis of the same participants found it did not slow the decline in memory, attention, language or executive function that comes with normal aging.2 A separate large European trial in older adults with memory complaints (GuidAge) reached the same conclusion for dementia prevention. When the good trials all agree, the question is closed.

Is there any real effect at all?

To be fair to the herb: a handful of small studies have reported minor short-term effects on things like blood flow or specific attention tasks, and ginkgo does have measurable pharmacology (it is a mild vasoactive and antioxidant). But these findings are inconsistent, often industry-linked, and far too small to justify the marketing — nothing here amounts to a usable cognitive benefit for a healthy person. There is slightly more discussion around symptomatic use in existing dementia and in tinnitus/vertigo, but even there the evidence is weak and not a reason for the general public to take it.

Safety — the bleeding caveat

Ginkgo is not benign filler. It has antiplatelet activity, and case reports and its pharmacology point to an increased bleeding risk when combined with warfarin, direct oral anticoagulants, aspirin or NSAIDs, or in the run-up to surgery — stop it at least a week or two before any operation.3 It can also lower the seizure threshold, so people with epilepsy should avoid it, and raw or roasted ginkgo seeds are genuinely toxic (this page is about the leaf extract). Given it does not deliver on its main promise, for most people the sensible risk-benefit call is simply not to bother.

Bottom line: a large six-year trial showed ginkgo does not prevent dementia or slow cognitive decline. Skip it for brain health — and be especially wary if you take blood thinners.

References

Adult research summary for education, not a prescription. These are food supplements, not treatments for disease.

  1. DeKosky ST, Williamson JD, Fitzpatrick AL, et al. Ginkgo biloba for prevention of dementia: a randomized controlled trial (GEM Study). JAMA 2008;300(19):2253–2262. pubmed.ncbi.nlm.nih.gov
  2. Snitz BE, O’Meara ES, Carlson MC, et al. Ginkgo biloba for preventing cognitive decline in older adults: a randomized trial. JAMA 2009;302(24):2663–2670. pubmed.ncbi.nlm.nih.gov
  3. Bent S, Goldberg H, Padula A, Avins AL. Spontaneous bleeding associated with Ginkgo biloba: a case report and systematic review of the literature. J Gen Intern Med 2005;20(7):657–661. pubmed.ncbi.nlm.nih.gov

This article summarises nutrition science for education. It is not a substitute for individual medical advice; consult a professional before starting a supplement, in pregnancy, or alongside medication.