Do Ginkgo supplements cause seizures? Is it safe?
High quality Ginkgo biloba extract dietary supplements have a good track record of safety and can be used in the recommended dose by most healthy adults without risk of seizures.
However, if you have epilepsy or a history of seizures, you may not want to use Ginkgo biloba extract without the recommendation of a health care professional who knows your health history and who can provide proper supervision.
The only seizure-related death I could find in the scientific literature for a person taking Ginkgo supplements was a 55-year-old male patient who had been prescribed anticonvulsant medications. There is evidence that Ginkgo supplementation can improve the clearance of anticonvulsant (and other) medications from the body, thereby reducing the amount of such medication in your system. (It appears to also clear some toxins.) In this case, the autopsy report did indeed reveal serum levels of anticonvulsants that were below the therapeutic level required.
Based on this case, it does not look like the Ginkgo supplement directly caused the seizure. However, it was responsible for reducing the patient's anticonvulsant medication below the required therapeutic level. There are a few other reports of non-fatal seizures in patients taking Ginkgo leaf supplements, but detailed case histories are not available in the scientific literature I have reviewed. As stated above, if you have epilepsy or a history of seizures, don't take Ginkgo supplements without the proper supervision. This would include, at a minimum, monitoring your blood level of any anticonvulsant medications you are taking.
Dietary supplements are made from Ginkgo leaf extract. Ginkgo seeds, which have traditionally been consumed as a food in some Asian cultures, can be poisonous. Ginkgotoxin can be present in unsafe amounts in Ginkgo seeds, and it is not recommended to consume Ginkgo seeds. Ginkgotoxin appears to be able to cause seizures. However, Ginkgo seeds are not used in any dietary supplements I am aware of.
Which brand is better?
At this time I will not recommend a specific brand, but I will give you my personal guidelines for choosing a high quality Ginkgo supplement:
- Certificate of Analysis ("COA") available for each batch. If you cannot get a current COA that has the batch number that matches the batch number on your bottle, that's a red flag.
- Independent laboratory analysis by a properly accredited laboratory for the key active ingredients, as reported in the COA.
- Ginkgo COA details include (at a minimum):
- Flavonol glycosides: not less than 22% (up to 36%)
- Terpene lactones (ginkgolides): not less than 5% (up to 12%)
- Ginkgolic acids: as low as possible. The EGb761 standard is < 5 ppm.
- Solvent residue: as low as possible. 500 ppm is a reasonable upper limit.
- Meets high standards for heavy metals and microbiological tests.
- Manufactured according to current GMP standards.
- Encapsulated without undesirable excipients.
- Warehoused properly before you receive it.
A good COA will include more details than I have summarized here. But if your Ginkgo supplement cannot meet the guidelines I have listed, look for something better.
In one study of 42 commercial Ginkgo supplements, only three of them were determined to be authentic. Review of Ginkgo biloba-induced toxicity. A valid COA, as described above, will resolve this concern.
Here is an article by Robert Ritch, MD. on the benefits of Ginkgo biloba extract (GBE) with an emphasis on eye health.