The ginkgo tree is sometimes called a living fossil. Its ancestors grew alongside the dinosaurs, and extracts of its fan-shaped leaves have been used in traditional Chinese medicine for centuries. In Europe and the United States, ginkgo became one of the best-selling supplements of all time on the promise that it sharpens memory and protects the aging brain.
Unlike many herbs, ginkgo has been tested in large, long, well-run trials. That makes it easier to give a clear answer, even if it is not the answer the supplement aisle wants. Short version: in the biggest trial ever run, ginkgo did not prevent dementia or slow memory decline in older adults.
Ginkgo at a glance: how strong is the evidence?
- 🧠 Preventing dementiaStrong evidence it does not work
- 📉 Slowing normal memory declineLarge trial found no benefit
- 🧓 Treating existing dementiaInconsistent, unreliable results
- 🩸 Bleeding risk with blood thinnersA real caution
- 🍃 Leaf extract vs raw seedsRaw seeds are toxic
🍃 What ginkgo is
Most research uses a standardized leaf extract called EGb 761, made to contain set amounts of flavonoids and terpene lactones. In the lab, these compounds act as antioxidants and seem to improve blood flow, which is the basis for the brain and circulation claims.
🧠 The GEM study: the biggest test of ginkgo
The Ginkgo Evaluation of Memory (GEM) study, funded largely by the NIH and published in JAMA in 2008, is the most important ginkgo trial ever run. Researchers gave 3,069 adults aged 75 or older either 120 mg of EGb 761 twice a day or a placebo, and followed them for a median of about six years.
The result was clear. Ginkgo did not reduce the rate of dementia overall, and it did not reduce Alzheimer’s disease specifically. The rates in the ginkgo and placebo groups were almost identical.
In 2009, the same team published a second analysis in JAMA looking at memory, attention, language and other thinking skills over time. Again, ginkgo did not slow cognitive decline compared with placebo.
🧓 What about people who already have dementia?
A 2009 Cochrane review pooled 36 trials of ginkgo for cognitive impairment and dementia. The older, smaller trials often looked positive, but the four most recent and largest trials did not show consistent benefit. The reviewers concluded that the evidence that ginkgo has a predictable and clinically meaningful benefit for people with dementia is inconsistent and unreliable.
Our read: ginkgo is one of the clearest examples of a supplement that looked promising in small studies and then disappointed when it was properly tested. If memory is your concern, the money is better spent elsewhere.
⚠️ Safety: what to know
- Bleeding risk. Ginkgo may thin the blood slightly. NCCIH advises caution if you take anticoagulants such as warfarin, antiplatelet drugs, or regular aspirin, and before surgery.
- Raw or roasted ginkgo seeds are toxic and can cause seizures. Supplements use the leaf, not the seed.
- Animal cancer findings. A study by the U.S. National Toxicology Program found that rats and mice given high doses of ginkgo extract developed liver and thyroid tumors. What this means for people taking normal doses is not known, but it is one more reason not to take ginkgo without a clear reason.
- Side effects can include headache, upset stomach, dizziness and allergic skin reactions.
- Pregnant or breastfeeding: avoid, due to the bleeding risk and lack of data.
💪 What actually protects memory
The 2024 Lancet Commission on dementia estimated that close to half of dementia cases worldwide may be linked to factors people can change. The ones with the best evidence:
- Treat high blood pressure, especially in midlife.
- Protect your hearing and use hearing aids if you need them.
- Stay physically active. Regular aerobic exercise is one of the best-supported habits for brain health.
- Do not smoke, and keep alcohol low.
- Stay socially connected and keep learning new things.
- Manage blood sugar and cholesterol, and get your vision checked.
If you still want to try ginkgo
Hawaii Pharm makes an alcohol-free liquid ginkgo leaf extract. Check with your doctor first if you take aspirin, a blood thinner or have surgery coming up, and stop it two weeks before any procedure.
Affiliate link. We may earn a commission if you buy, at no extra cost to you. Price and availability are set by the retailer and can change.
🔍 Why the small studies looked so good
Ginkgo’s story is a useful lesson in reading health research. Many of the early trials were small, short, run in a single clinic and sometimes funded by the extract’s maker. Small studies are more likely to produce dramatic results by chance, and positive results are more likely to be published than negative ones. When the NIH funded a trial big enough and long enough to give a reliable answer, the effect disappeared.
That pattern shows up again and again with supplements, which is why we put the most weight on the largest, longest, independent trials.
🏷️ If you decide to try it anyway
- Look for leaf extract, never seed products.
- Check the strength. The major trials used 120 mg of standardized extract twice a day. Liquid extracts are measured differently, so follow the label.
- Tell every doctor and dentist you take it, especially before procedures.
- Set a review date. Decide in advance what improvement you are looking for and stop after two or three months if you do not see it.
🤔 Ginkgo for circulation in the legs
Ginkgo is also sold for intermittent claudication, the leg pain on walking caused by narrowed arteries. A Cochrane review of these trials found no clinically significant benefit. Supervised walking programs and medical treatment have far better evidence, so talk to your doctor if you get leg pain when you walk.
Frequently asked questions
Can ginkgo help a young, healthy person focus?
There are small studies in healthy young adults, but the results are mixed and short-term. There is no strong evidence that ginkgo sharpens focus in people without memory problems.
Does ginkgo help tinnitus?
Reviews of the trials have not found convincing evidence that ginkgo improves ringing in the ears.
Is there a better supplement for memory?
No supplement has strong evidence for preventing dementia. If you are worried about your memory, see your doctor, since causes such as low vitamin B12, thyroid problems, depression and medication side effects are treatable.
The honest bottom line
Ginkgo has been tested about as thoroughly as any herb, and the largest, longest trial found it did not prevent dementia or slow memory decline in older adults. It also carries a bleeding risk for people on blood thinners. If brain health is your goal, blood pressure control, exercise, hearing care and social connection have far better evidence.
Studies and sources
- DeKosky ST et al. (2008). Ginkgo biloba for prevention of dementia: a randomized controlled trial. JAMA, via PubMed.
- Snitz BE et al. (2009). Ginkgo biloba for preventing cognitive decline in older adults: a randomized trial. JAMA, via PubMed.
- Birks J, Grimley Evans J (2009). Ginkgo biloba for cognitive impairment and dementia. Cochrane Database of Systematic Reviews, via PubMed.
- Ginkgo. NCCIH.
This article is for general education and is not medical advice. Talk to your doctor or pharmacist before starting a supplement, especially if you take medication or have a health condition. These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.
