ginkgo
Meaning of ginkgo: A leaf extract from an ancient tree, sold widely for memory, and repeatedly found no better than placebo in large trials.
Definition of ginkgo
Ginkgo is a herbal product made from the fan shaped leaves of Ginkgo biloba, a tree species that has survived largely unchanged for millions of years. Standardized leaf extracts contain flavonoids and terpene compounds, and are sold as supplements for memory, circulation and ringing in the ears. Large controlled trials have not shown that ginkgo prevents dementia.
What is it taken for, and does it work?
| Claim | What the research found |
|---|---|
| Preventing dementia in older adults | A large multi-year trial found no reduction in new cases |
| Slowing established Alzheimer disease | Results conflict, and any effect found is small |
| Ringing in the ears | No reliable benefit over placebo |
| Leg pain from narrowed arteries | Walking distance improved little or not at all |
| Memory in healthy adults | No convincing effect |
How is it supposed to act?
The extract holds two useful looking groups of compounds. Flavonoids mop up reactive molecules that damage cells. Terpene lactones, including one named ginkgolide B, interfere with a signal that makes platelets clump, which slightly widens small vessels and slows clotting. That second action is the plausible basis for the old claim about circulation, and it is also the source of the main safety concern. Laboratory activity of this kind is a long way from a measurable benefit in people, and the trials illustrate the gap.
What are the safety concerns?
Because the extract slows platelets, bleeding is the recognized risk, and it rises when ginkgo is combined with anticoagulants, aspirin or similar drugs, or taken close to surgery or dental work. Seizures have been reported, mainly in people who already have epilepsy. Raw or roasted ginkgo seeds are a separate matter from the leaf extract and contain a natural toxin that can cause seizures, particularly in children. Supplements are not tested before sale the way medicines are, so the amount of active compound varies between products and some have been found adulterated. Mild stomach upset, headache and dizziness are the usual complaints.
Also known as
Used in a sentence
The medication history included ginkgo, which was noted before the planned surgery because of bleeding risk.
Good to know
Ginkgo interferes with platelet clumping, so the practical concern is bleeding rather than the memory benefit the product is marketed for, and the seeds carry a seizure risk that the leaf extract does not.