Ginkgo Biloba

What it is

Ginkgo biloba is an extract from the leaves of the ginkgo tree, standardised in products such as EGb 761 and sold as a supplement for memory and circulation [1]. Trials in older adults have used 120 mg twice a day (240 mg a day) for up to six years [1] [2], while a 2026 comparison in healthy adults grouped doses from 60 mg a day up to 240 mg a day and above [3].

What the research says

A 2023 systematic review of plant nootropics concluded ginkgo was the most relevant option for perceptual and motor functions [4]. For memory, a 2026 network meta-analysis of 29 trials (2,107 healthy adults) ranked both ginkgo doses below high-dose bacopa on working memory [3], and a review of herbal supplements in older adults found ginkgo's effects on thinking "consistently unclear", with most ginkgo trials at high risk of bias [5]. A small 2008 pilot trial (118 people, 42 months) found no reduced risk of progression to cognitive impairment in its main analysis [6]. For prevention, the Ginkgo Evaluation of Memory study gave 3,069 adults aged 75 and older 240 mg a day for a median of 6.1 years: dementia rates were similar to placebo (hazard ratio 1.12, 95% CI 0.94-1.33), and an analysis of the same trial found no difference in the rate of decline on memory, attention, language or executive-function tests [1] [2]. The French GuidAge trial (2,854 adults with memory complaints, five years) likewise found no reduction in Alzheimer's diagnoses (hazard ratio 0.84, 95% CI 0.60-1.18) [7].

Doses used in studies

Prevention trials used 120 mg twice a day (240 mg a day) of standardised extract for five to six years [1] [7]. The 2026 review grouped ginkgo doses as 60 to under 240 mg a day and 240 mg a day or more [3].

Safety and interactions

• Common side effects: in trials of older adults, ginkgo's side effects matched placebo; reported complaints included stomach upset, dizziness, headaches and sleep disturbance [5].
• Upper limits: no established upper intake limit; trials have used 240 mg a day for over six years, with side effects similar to placebo [1].
• Bleeding and interactions: a meta-analysis of 18 trials (1,985 adults) found no clear effect on clotting tests and no increased bleeding risk from standard extracts [8], but a systematic review lists ginkgo among supplements reported to interact with warfarin, with bleeding events in some reports [9], and a small pilot trial observed more strokes and mini-strokes in the ginkgo group [6].
• Pregnancy and breastfeeding: ginkgo is advised against in pregnancy — it may prolong bleeding time around labour — and its safety during breastfeeding is unknown [10].
• Conditions: people taking blood thinners or with a bleeding disorder should check with a doctor first [9].

Caveats and open questions

Ginkgo has been tested for decades without producing a consistent cognitive benefit in healthy people [5], and the prevention trials found no dementia benefit [1] [7]. The signal for perceptual and motor tasks comes from heterogeneous studies rather than a pooled trial result [4].