Ginkgo biloba is a tree with leaves that have been used in traditional Chinese medicine for centuries to treat ailments of the brain, heart, and lungs. While ginkgo biloba teas and tinctures are most common in Eastern medicine, it is also available as an herbal supplement. In clinical trials, ginkgo biloba failed to prevent cognitive decline or dementia. It might slightly improve memory in those with dementia, though the evidence is mixed. It is generally considered safe, though it does pose some health risks to specific groups.
Multiple meta-analyses and systematic reviews have examined the effects of ginkgo biloba on cognitive functions in healthy adults as well as in dementia patients. Our search identified:
• 3 meta-analyses of clinical trials in cognitively healthy adults
• 8 meta-analyses of clinical trials in cognitively impaired to severely demented patients
• Numerous preclinical studies on possible mechanisms of action
Multiple clinical trials involving thousands of patients have conclusively shown that treatment with ginkgo biloba for up to six years does not prevent cognitive decline or dementia, including Alzheimer’s disease [1-4]. This is disappointing since preclinical studies indicated that gingko biloba contains several components that improve brain blood flow and mitochondrial function . (Mitochondria are the "power plants" of human cells that often malfunction with age and in diseases such as Alzheimer's.)
There is very limited evidence on ginkgo biloba's effects on APOE4 patients. However in a combination drug trial, both carriers and non-carriers showed improved cognitive function in response to supplementation . To learn more about how APOE4 might affect your health, visit our APOE information page.
Ginkgo biloba may slightly improve memory and cognitive function for people with memory problems or dementia. However, clinical guidelines are mixed. While the World Federation of Societies of Biological Psychiatry guidelines suggest that a certain ginkgo biloba extract may be used to treat dementia symptoms, the British Association for Psychopharmacology and the American Academy of Family Physician concluded that its benefits are inconsistent and unreliable.
Similarly, clinical trial results are mixed. A 2009 high-quality meta-analysis concluded that the effects of ginkgo biloba on cognitive impairment and dementia were inconsistent and unreliable . There are two other recent meta-analyses in dementia patients. In one analysis, seven studies showed that patients using ginkgo had improved scores on certain cognitive performance tests. Two studies in the same analysis using different assessments, however, did not show a statistically significant difference . Another meta-analysis of patients with mild cognitive impairment and Alzheimer's disease showed that after 24 weeks of ginkgo, in combination with conventional medicine, they improved cognitive performance scores .
Ginkgo biloba is usually safe when properly used by healthy adults . Although some clinical trials suggested ginkgo might raise the risk of stomach bleeding in older adults, a meta-analysis of numerous clinical trials found no such association . Because ginkgo can dilate blood vessels, it may not be safe in patients taking medication for high blood pressure. It may also be unsafe for children, people with diabetes, or women trying to become pregnant.
NOTE: This is not a comprehensive safety evaluation or complete list of potentially harmful drug interactions. It is important to discuss safety issues with your physician before taking any new supplement or medication.
Standardized ginkgo biloba extracts are generally safe for most people at oral doses of 120 to 240 mg per day. Although some ginkgo biloba extracts are sold over-the-counter, the EGb761® formulations tested in clinical trials are only available by prescription.
United States Pharmacopeial Convention (USP) and FDA Information on Dietary Supplements offer information on the quality of specific supplements and can assist in finding a trusted brand.
National Center for Complementary and Alternative Medicine and University of Maryland offer additional information on ginkgo biloba as a dietary supplement, including dosage and safety.
Check for drug-drug and drug-supplement interactions on Drugs.com.