Ginkgo Biloba

What is ginkgo biloba?

NCCIH describes ginkgo as a deciduous tree known as a “living fossil,” the last remaining species of a primitive plant family; it has long been used in Chinese medicine for cough, diarrhea, and other conditions. The form most used today is the leaf part, usually as an extract. ^[1] As a supplement, it is marketed for many conditions such as anxiety, heart disease, cognitive impairment and dementia, diabetes, premenstrual syndrome, schizophrenia, and tinnitus; it has also been presented with the claim of improving cognitive performance in healthy people. ^[1]

The difference between products matters: the Restricted Substances List in Türkiye defines separate limits for two separate groups of marker compounds from ginkgo extract (ginkgo flavonoid glycosides and terpene lactones). ^[10] A standardized extract used in a study cannot be considered directly equivalent to another product bearing the same plant name.

Role in the body and purpose of use

Ginkgo is not a nutrient; it has no required function or deficiency in the body. Marketing claims concern possible effects on cognitive function and circulation; the Cochrane review says “neuroprotective effects are biologically plausible,” but this is the review’s rationale, not evidence. ^[4] In the sections below, each claim is given separately, with whom it was measured in and what was found.

Does ginkgo prevent dementia?

The GEM (Ginkgo Evaluation of Memory) study is a randomized, double-blind, placebo-controlled RCT conducted in the US at 5 academic centers between 2000 and 2008. A total of 3,069 volunteers aged 75 and over, with normal cognitive function (n = 2,587) or mild cognitive impairment (MCI) (n = 482), were assigned to a ginkgo extract group (n = 1,545) or a placebo group (n = 1,524); median follow-up was 6.1 years. Of the 523 people who developed dementia, 277 were in the ginkgo group and 246 in the placebo group. The hazard ratio was 1.12 (95% CI 0.94–1.33; p = 0.21) for all-cause dementia, 1.16 (95% CI 0.97–1.39; p = 0.11) for Alzheimer’s disease, and 1.13 (95% CI 0.85–1.50) for progression to dementia in those with MCI. Adverse effect profiles were similar in the two groups, and the study was NIH-supported. ^[2] There is an erratum record in PubMed for the article (JAMA 2008;300:2730).

The GuidAge study lasted 5 years in France in adults aged 70 and over who spontaneously reported memory complaints to a primary care physician: 2,854 people were randomized, 1,406 received ginkgo and 1,414 received placebo. By the fifth year, probable Alzheimer’s disease had been diagnosed in 61 people in the ginkgo group and 73 in the placebo group (1.2 and 1.4 per 100 person-years; HR 0.84; 95% CI 0.60–1.18; p = 0.306); the risk was not proportional over time. Deaths (76 and 82) and stroke (65 and 60; RR 1.12; 95% CI 0.77–1.63) were similar in the two groups. According to the PubMed record, funding for the study was provided by a pharmaceutical company. ^[3]

NCCIH reports that in three large studies, including GEM, ginkgo extract supplementation did not reduce the risk of dementia in older adults with normal cognitive function or mild cognitive impairment; ginkgo has not been shown to prevent dementia or slow its progression. ^[1]

Is ginkgo effective for mild cognitive impairment and dementia symptoms?

The 2026 update of the Cochrane review (Wieland et al., search December 8, 2022; updated November 18, 2024) included RCTs comparing ginkgo with placebo, usual care, or other treatments in people with cognitive complaints or a diagnosis of MCI or dementia: 82 studies, 10,613 participants; 72 studies (9,783 participants) had analyzable data, and only four studies were at low risk of bias in all domains. ^[4]

Subjective cognitive complaint. Three studies (597 participants) were examined; in the single six-month study (197 participants), it was uncertain whether there was an effect on global clinical status (mean difference 0.00; 95% CI −0.33 to 0.33; very low certainty). In a larger three-month study, the risk of adverse events was reported to possibly be higher with ginkgo. ^[4]

Mild cognitive impairment (MCI). Twelve studies (1,913 participants): moderate-certainty evidence at 6 months showed that ginkgo likely has little or no effect on global clinical status (Clinical Dementia Rating scale; mean difference −0.03; 95% CI −0.06 to 0.01; 3 studies), cognitive function (ADAS-cog; −0.07; 95% CI −0.67 to 0.51; 2 studies), and activities of daily living (−0.05; 95% CI −0.29 to 0.19; 1 study). There was little or no difference in serious adverse events (RR 0.95; 95% CI 0.82–1.09; 3 studies; high certainty). ^[4]

Dementia. Thirteen studies (3,288 participants): low-certainty evidence suggested that at 6 months, people taking ginkgo may have somewhat better global clinical status, cognitive function (mean difference −1.86 on the Syndrom-Kurztest; 95% CI −3.48 to −0.24; 9 studies), and activities of daily living; between-study variation was very high (I² 88–96%). There was likely no difference in adverse events (RR 0.95; 95% CI 0.90–1.00; 9 studies; moderate certainty). ^[4] The authors’ conclusion: there may be small to moderate benefits at 6 months in people with dementia, and little or no effect is expected in MCI. NCCIH also states that ginkgo extract, particularly at high doses, may provide a modest benefit in dementia symptoms, but the evidence is inconsistent. ^[1]

Does ginkgo improve memory and attention in healthy people?

NCCIH reports that it is uncertain whether ginkgo supplements marketed for “brain health” affect cognitive performance in healthy people, and that most research on this topic is of low quality. ^[1] Another herbal supplement carrying a cognitive function claim is covered on a separate page: Ginseng.

Does ginkgo help tinnitus?

The Cochrane review (Sereda et al., search June 7, 2022) included RCTs comparing ginkgo with placebo, no intervention, or information in adults and children with tinnitus: 12 studies, 1,915 participants; most had a high or unclear risk of bias. By pooling two studies, the mean difference in tinnitus severity (Tinnitus Handicap Inventory, 0–100) at 3–6 months was −1.35 (95% CI −8.26 to 5.55; 85 participants; very low certainty): ginkgo may have little or no effect, but the evidence is very uncertain. In four studies (1,154 participants), there was little or no difference in the risk of bleeding or seizures, and no serious adverse effects were reported in either group (low certainty). The authors concluded that there is uncertainty about benefit and harm. ^[5] NCCIH, however, reports that ginkgo is not helpful in relieving tinnitus symptoms. ^[1]

Does ginkgo increase bleeding risk?

There are two different types of evidence on the topic. The meta-analysis by Kellermann and Kloft covered 18 RCTs (1,985 adults; 87% with dementia, peripheral arterial disease, or diabetes, 13% healthy volunteers). No significant effect was found on ADP-induced platelet aggregation, fibrinogen, aPTT, and PT; blood viscosity decreased (mean difference −1.03 mPa·s). The authors concluded that, according to these hemostasis measures, standardized extract did not show a higher bleeding risk. ^[6]

The review by Bent and colleagues, by contrast, examined 15 published bleeding cases temporally associated with ginkgo use; most were in people with serious disease (8 intracranial hemorrhages), 13 had another bleeding risk factor, and only 6 reports explicitly stated that ginkgo was stopped and bleeding did not recur. The authors concluded in a structured assessment that there was a possible causal relationship. ^[7] NCCIH reports that ginkgo may increase the risk of bleeding in people taking anticoagulants such as warfarin. ^[1] These three statements do not fully coincide: laboratory measures did not change, whereas case reports and an institutional summary pointed to a possible risk.

What other side effects and risk situations does ginkgo have?

According to NCCIH, ginkgo leaf extracts are likely safe orally in moderate amounts in most adults and have been used safely in research lasting up to 6 years; the most common side effects are dizziness, digestive symptoms, and headache. Fresh ginkgo seeds are toxic when taken orally; serious side effects have also been seen in people who consumed roasted seeds or the raw plant. Ginkgo may also interact with other medicines. It may not be safe in pregnancy; use near delivery is noted to potentially cause premature birth or excessive bleeding at delivery, and safety in breastfeeding is unknown. ^[1]

In animal studies, the US National Toxicology Program (NTP) reported, in a 2-year gavage study, an increase in the incidence of hepatocellular adenoma, carcinoma, and hepatoblastoma in B6C3F1/N mice, and in F344/N rats a slight increase in thyroid follicular cell adenoma, adenoma of the nasal respiratory epithelium in two female rats, and an increase in the incidence of mononuclear cell leukemia in males; in addition, the extract was found mutagenic in bacterial tests. These findings come from a rodent study; they cannot be directly transferred to tumor risk in humans. ^[8]

What is the status of ginkgo in Türkiye?

In the July 16, 2026 update of the Ministry of Agriculture and Forestry Plant List, Ginkgo biloba (“Ginkgo, Mabet Ağacı”; leaf) is listed as positive (P); the list shows only the leaf as the part used. ^[9] In the September 21, 2026 version of the Restricted Substances List for Food Supplements, 115 mg/day for “Ginkgo flavonoid glycosides (from Ginkgo biloba extract)” and 29 mg/day for “Terpene lactones (from Ginkgo biloba extract)” are written in the ages 11 and over maximum column (published June 27, 2016); the ages 4–10 columns are empty. ^[10] These limits are amounts of marker compounds; they are not in the same unit as the total extract weight used in studies. Food supplements are covered separately on the Supplement regulation in Türkiye page. This guide does not recommend products or places of purchase and does not set personal doses.

Evidence table: claim, population, and limits