Ginkgo biloba is a plant-based supplement that acts primarily as an antioxidant and circulation booster, with its strongest evidence supporting modest benefits for people with mild dementia. It contains two groups of active compounds: flavonoids (about 24% of standardized extract) and terpene lactones (about 6%), which work together to scavenge damaging molecules in cells, increase blood flow, and raise levels of certain brain chemicals. Most research uses a standardized extract called EGb 761, typically taken at 120 to 240 mg per day.
How Ginkgo Works in the Body
Ginkgo’s flavonoids and terpene compounds do three things at the cellular level. First, they directly neutralize free radicals, the unstable molecules that damage cells over time. Second, they boost your body’s own antioxidant defenses, increasing the activity of protective enzymes in the brain. Third, they protect mitochondria, the energy-producing structures inside your cells, from losing their electrical charge during stress. When mitochondria lose that charge, cells begin to self-destruct. Ginkgo extract has been shown to prevent this cascade in both brain and heart cells.
In the brain specifically, ginkgo raises dopamine levels. A study published in the British Journal of Pharmacology found that after 14 days of treatment, the flavonoid portion of ginkgo extract significantly increased dopamine in the prefrontal cortex, the region responsible for planning, decision-making, and working memory. The terpene compounds produced a smaller but still measurable increase. This dopamine effect may explain some of the cognitive benefits people report.
Effects on Memory and Cognitive Decline
The evidence for ginkgo and cognition depends heavily on who’s taking it. For people already experiencing mild dementia from Alzheimer’s disease or vascular causes, ginkgo at 240 mg per day for at least 24 weeks has shown meaningful improvements across multiple clinical trials. These studies measured real outcomes: better scores on memory tests, improved daily functioning, and reduced behavioral symptoms like agitation and depression. Several trials found ginkgo performed comparably to standard dementia medications on cognitive assessments.
A review of randomized clinical trials in Frontiers in Pharmacology found enough positive evidence that expert consensus guidelines now list ginkgo extract alongside conventional medications as a treatment option for Alzheimer’s disease and vascular dementia. It’s also considered a reasonable option for mild cognitive impairment, the stage between normal aging and dementia.
For healthy people hoping to sharpen their thinking, the picture is much less clear. The National Institutes of Health states that it’s uncertain whether ginkgo actually influences cognitive performance in healthy adults, and much of the research on this question is low quality. Ginkgo also does not appear to prevent dementia from developing in the first place. So while it may help once cognitive decline has started, there’s no strong case for taking it as a preventive measure.
Anxiety Reduction
One well-designed trial tested ginkgo in 107 patients with generalized anxiety disorder or adjustment disorder with anxious mood. Participants received either 480 mg, 240 mg, or a placebo daily for four weeks. Anxiety scores dropped by 14.3 points in the high-dose group and 12.1 points in the low-dose group, compared to only 7.8 points with placebo. Both ginkgo doses were significantly better than placebo, and there was a clear dose-response pattern: more ginkgo, less anxiety. Ginkgo also outperformed placebo on every secondary measure, including tension, aggression, and patients’ own ratings of improvement.
This is a single trial, so it’s far from conclusive. But the results were strong enough to suggest ginkgo has genuine calming effects beyond just placebo response, possibly related to its influence on dopamine and its ability to reduce oxidative stress in the brain.
Blood Flow and Circulation
Ginkgo increases nitric oxide levels in blood vessels, which causes them to relax and widen. This improves microcirculation, the flow of blood through your smallest vessels. The effect has been measured in the eyes, brain, and limbs.
For peripheral artery disease, where narrowed leg arteries cause pain during walking, ginkgo’s benefits are disappointing. A Cochrane review of 11 trials involving 477 participants found that ginkgo users could walk only about 64.5 meters farther than placebo users, a difference that wasn’t statistically significant. The review concluded there’s no evidence of a clinically meaningful benefit for this condition.
Eye Health and Glaucoma
Ginkgo’s circulation-boosting properties have drawn interest for eye conditions, particularly normal-tension glaucoma, where the optic nerve deteriorates even though eye pressure is normal. The theory is that poor blood flow to the optic nerve contributes to damage, and ginkgo might help by improving that flow.
Several small studies support this idea. Healthy volunteers who took ginkgo for as little as two days showed increased blood flow velocity in the arteries supplying the eye. After four weeks, blood flow and microcirculation around the optic nerve increased measurably. In one long-term study with an average follow-up of over 12 years, ginkgo slowed the progression of visual field loss in normal-tension glaucoma patients. Another study found improved visual acuity after nearly two years of daily use.
However, a systematic review pooling data from eight studies and 428 patients found that ginkgo did not significantly improve eye pressure, visual field scores, or heart rate from baseline to follow-up. The evidence is promising but inconsistent, and the studies so far have been small with variable follow-up periods.
Dosage Used in Research
Nearly all clinical research uses the standardized EGb 761 extract, which contains 24% flavonoid glycosides and 6% terpene lactones. The standard dose is 120 mg per day, typically split into 40 mg three times daily or 80 mg twice daily. For dementia and anxiety, studies showing benefit have used 240 mg per day, which is the maximum recommended dose. Benefits for cognitive decline required at least 24 weeks of consistent use before becoming apparent.
Safety and Bleeding Risk
Ginkgo is generally well tolerated, but it carries a real interaction risk with blood-thinning medications. The terpene compounds in ginkgo can reduce platelet aggregation, making blood slightly less likely to clot. For most people taking ginkgo alone, this doesn’t appear to cause problems. A meta-analysis of 18 randomized controlled trials found that while ginkgo reduced blood viscosity, it didn’t affect most clotting factors, and the authors concluded there was no higher bleeding risk from ginkgo on its own.
The concern changes significantly when ginkgo is combined with warfarin or similar anticoagulant medications. A large study of veterans taking warfarin found that those who also took ginkgo had a 38% higher risk of a bleeding event compared to those on warfarin alone. This is a meaningful increase. If you take any blood-thinning medication, including common over-the-counter options like aspirin, ginkgo adds to the anticoagulant effect in a way that can become clinically significant. The same caution applies before surgery, where unexpected bleeding is a serious concern.