Ginkgo biloba — the maidenhair tree — is one of the oldest living tree species on Earth, with fossils dating back 270 million years. Individual trees can live for over 1,000 years and have survived extreme conditions, including the atomic bombing of Hiroshima in 1945, where several ginkgo trees within 2 km of the hypocentre survived and continue to grow. In traditional Chinese medicine, ginkgo seeds have been used for thousands of years for respiratory and circulatory conditions. Modern scientific interest focuses on a standardised extract of the leaves.
The standardised extract: EGb 761
Most clinical research on ginkgo has used a specific standardised extract called EGb 761 (also marketed as Tebonin and Tanakan). This extract is standardised to contain 24% flavone glycosides (primarily quercetin, kaempferol, and isorhamnetin glycosides) and 6% terpene trilactones (ginkgolides A, B, and C, and bilobalide). This standardisation is important — unstandardised ginkgo products may not contain the same active compounds in the same ratios.
Mechanisms of action
Ginkgo's biological effects operate through several mechanisms:
- Antioxidant: Flavonoids in ginkgo scavenge free radicals in both aqueous and lipid environments, protecting cell membranes and neural tissue from oxidative stress.
- Platelet-activating factor (PAF) antagonism: Ginkgolides — particularly ginkgolide B — are potent natural antagonists of PAF, a signalling molecule involved in platelet aggregation and inflammation. This effect may contribute to ginkgo's influence on blood viscosity and microcirculation.
- Neurotransmitter modulation: Ginkgo influences several neurotransmitter systems, including serotonin, dopamine, and acetylcholine reuptake, which may partly explain cognitive effects seen in some studies.
- Vasodilation: Ginkgo promotes the release of nitric oxide and prostacyclin, contributing to vasodilation and improved peripheral circulation.
Clinical evidence
Ginkgo has been most extensively studied for dementia, age-related cognitive decline, and peripheral arterial disease (PAD). Evidence for dementia is mixed: a major US trial (GEM study, n=3,069, follow-up 6 years) found no significant reduction in dementia incidence, while some European trials with EGb 761 show modest improvements in cognitive and neuropsychiatric symptoms in existing dementia patients. For peripheral arterial disease, meta-analyses find meaningful improvements in pain-free walking distance in patients with claudication.
For peripheral arterial disease, meta-analyses find meaningful improvements in pain-free walking distance in claudication patients — an effect attributed to improved microcirculation.
Safety note
Ginkgo has antiplatelet properties and should be used with caution alongside blood-thinning medications (aspirin, warfarin, anticoagulants). It should generally be discontinued before surgery. Ginkgo seeds contain ginkgotoxin (4'-O-methylpyridoxine), which is toxic in large amounts, but this is not present in leaf extracts.
Ginkgo biloba in Lebanon
Supplements & More carries standardised ginkgo biloba extract from US brands, available with cash on delivery across Lebanon.