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Nootropics

Ginkgo Biloba

A widely marketed botanical that has not prevented dementia or slowed normal cognitive decline in large, rigorous trials.

Insufficient
Evidence rating
Evidence review

What the evidence says

Ginkgo biloba extracts are marketed for memory and circulation, but product standardization and indication matter. Evidence from a named standardized extract cannot be transferred automatically to every leaf powder, tea, or supplement blend.[5][4]

The Ginkgo Evaluation of Memory trial randomized 3,069 adults aged 75 or older to 120 mg twice daily or placebo. Over a median 6.1 years, ginkgo did not reduce overall dementia or Alzheimer disease incidence.[1]

A companion analysis found no slower decline in memory, attention, visuospatial ability, language, or executive function. A six-week randomized study in healthy older adults likewise found no measurable memory benefit, arguing against its use as a routine enhancer.[2][3]

Reviews of symptomatic dementia trials report possible small benefits in some datasets, but heterogeneity, selective products, short follow-up, and publication limitations keep certainty below that of established dementia care. Ginkgo should not delay diagnostic assessment or evidence-based treatment.[4][5]

Potential benefits

  • Some standardized-extract trials report small short-term symptom changes in dementia, but the clinical importance is uncertain.[4]
  • Large long-term trials provide unusually clear evidence against dementia-prevention claims.[1][2]

Side effects and cautions

  • Headache, dizziness, gastrointestinal symptoms, and allergic skin reactions can occur.[5]
  • Bleeding risk and interactions are concerns, especially with anticoagulant or antiplatelet medicines and around surgery.[5]
How we scored it

Evidence breakdown

Small dementia studies remain inconsistent, while large prevention trials and healthy-adult studies do not support routine cognitive use.

Clinical relevanceHigh

Large studies measured dementia incidence and longitudinal cognitive decline.

Study qualityHigh

The negative prevention evidence includes a 3,069-person randomized trial.

Safety dataModerate

Short-term use is usually tolerated, but bleeding interactions and product variability matter.

References

Full source list

  1. Ginkgo biloba for prevention of dementia: a randomized controlled trial

    JAMA · 2008

  2. Ginkgo biloba for preventing cognitive decline in older adults: a randomized trial

    JAMA · 2009

  3. Ginkgo for memory enhancement: a randomized controlled trial

    JAMA · 2002

  4. Ginkgo biloba extract for dementia: a systematic review

    Aging and Disease · 2016

  5. Ginkgo: Usefulness and Safety

    National Center for Complementary and Integrative Health · 2025