Ginkgo biloba has real, measurable effects for some conditions, but not the ones most people buy it for. The biggest and most rigorous trial ever conducted on ginkgo, the Ginkgo Evaluation of Memory (GEM) study published in JAMA, found that 240 mg daily did not prevent dementia or slow cognitive decline in older adults. Yet smaller, well-designed trials show genuine benefits for mild dementia that already exists, for anxiety, and for tinnitus. The answer depends entirely on what you’re hoping it will do.
The Case for Memory and Brain Health
Most people reach for ginkgo because they want a sharper memory or protection against cognitive decline. The evidence here is split in a way that matters. If you’re a healthy older adult trying to prevent dementia, ginkgo does not appear to help. The GEM study followed over 3,000 adults aged 75 and older for a median of six years, giving half of them 120 mg of ginkgo twice daily and the other half a placebo. There was no difference in dementia rates between the two groups, and no measurable effect on memory, attention, language, or processing speed.
The picture changes for people who already have mild dementia. A meta-analysis published in European Psychiatry found that 240 mg daily of the standardized extract EGb 761 was significantly better than placebo for cognition, daily functioning, and quality of life in people with mild dementia, with medium to large effect sizes. This is a meaningful distinction: ginkgo may support a brain that’s already struggling without doing much for one that’s functioning normally.
How Ginkgo Works in the Body
Ginkgo’s active compounds fall into two groups: flavone glycosides and terpene lactones. The flavone glycosides act as antioxidants, neutralizing molecules that damage cells. The terpene lactones reduce inflammation and inhibit a substance called platelet-activating factor, which plays a role in blood clotting and inflammatory responses. Together, these compounds increase blood flow to the brain by relaxing blood vessels. That improved circulation is the most likely explanation for why ginkgo helps people with existing cognitive problems but not healthy brains that already have adequate blood supply.
Anxiety Reduction
One of the more surprising findings in ginkgo research involves anxiety. In a randomized, double-blind trial of 107 patients with generalized anxiety disorder, those taking 480 mg daily saw their anxiety scores drop by 14.3 points on a standard clinical scale, compared to a 7.8-point drop in the placebo group. That’s nearly double the improvement. Even the lower dose of 240 mg produced a statistically significant benefit, with a 12.1-point reduction. The study also found a clear dose-response relationship: more ginkgo meant less anxiety. This is a single trial, so it’s not as robust as the memory research, but the results were strong enough to be notable.
Tinnitus Relief
For people with persistent ringing in the ears, ginkgo has some of the most consistent positive evidence of any supplement. A systematic review of randomized, placebo-controlled trials found that the standardized extract EGb 761 was statistically superior to placebo in all eight trials examined. In studies where tinnitus was the primary complaint, 31% of ginkgo users reported improvement compared to 14% on placebo. In another trial, 40% of ginkgo users rated themselves as “much improved” versus 24% on placebo, and the time until half of patients experienced significant improvement was 70 days for ginkgo compared to 119 days for placebo.
One important caveat: these positive results came specifically from trials using the standardized EGb 761 extract. Studies using other ginkgo preparations showed no effect, which points to a quality control issue covered below.
Eye Health Claims Fall Short
Ginkgo is sometimes marketed for glaucoma and eye health, based on its blood-flow-enhancing properties. A systematic review in PLOS One found this claim doesn’t hold up. Ginkgo had no significant effect on eye pressure, visual field measurements, or heart rate compared to placebo. There were a couple of individual studies suggesting possible benefits for a specific type of glaucoma called normal-tension glaucoma, including one with a 12-year follow-up showing slower visual field damage. But the overall body of evidence showed no superiority over placebo for eye health in general.
How Long Before You Notice Anything
If ginkgo is going to work for you, don’t expect overnight results. In a double-blind trial tracking 12 different symptoms, differences between ginkgo and placebo were minimal at two weeks. The real separation happened between weeks two and four, when about two-thirds of ginkgo users showed improvement compared to roughly one-fifth on placebo. By six weeks, 11 of the 12 measured symptoms showed significant differences. Most clinical trials run for at least 8 to 12 weeks, and some dementia studies extend to 6 months or longer. A reasonable trial period is at least 4 to 6 weeks before deciding whether it’s doing anything for you.
Not All Ginkgo Products Are the Same
This is where most consumers go wrong. The extract used in nearly all positive clinical trials, called EGb 761, is standardized to contain approximately 24% flavone glycosides and 6% terpene lactones. These percentages aren’t arbitrary; they reflect the specific ratios of active compounds that have been tested and shown to work. A generic ginkgo supplement from a discount shelf may contain wildly different concentrations of these compounds, or include parts of the plant that weren’t used in research. If a product label doesn’t specify standardization to 24% flavone glycosides and 6% terpene lactones, you have no way to compare it to what was actually studied.
The effective dosage in clinical trials ranges from 120 mg to 240 mg daily for most conditions, with the anxiety trial using doses up to 480 mg. For mild dementia, 240 mg daily is the best-studied dose.
Safety and Bleeding Risk
Ginkgo is generally well tolerated. The most common side effects are mild: headache, heart palpitations, digestive upset, constipation, and occasional skin reactions. These occur at rates similar to placebo in most trials.
The serious concern is bleeding. Ginkgo reduces platelet aggregation, meaning it makes your blood less likely to clot. For most healthy people, this isn’t dangerous. But a large study of veterans taking the blood thinner warfarin found that adding ginkgo increased the risk of a bleeding event by 38%. That’s a clinically significant increase. If you take warfarin, aspirin, or other blood thinners, ginkgo is a real risk. The same applies before surgery, since impaired clotting can lead to excessive bleeding during and after procedures.
The Bottom Line on What Works
Ginkgo biloba is not the universal brain booster it’s marketed as. It does not prevent dementia in healthy older adults, and it does not sharpen memory in people with normal cognition. Where it does show real, replicated benefits is in managing symptoms of existing mild dementia, reducing anxiety, and alleviating tinnitus. The critical variable is using a standardized extract at the right dose for a long enough period. A cheap, unstandardized supplement taken for a week will almost certainly do nothing, which likely explains the disconnect between the supplement aisle hype and what many people actually experience.