Ginkgo Biloba – What is it:
Ginkgo biloba is a tree that grows wild in China and is known for its distinctly shaped duck feet leaves. The extract from this tree is known to contain two active chemicals: flavonoids, which act as antioxidants; and terpenoids, which have a blood thinning effect.
There is evidence that Ginkgo biloba extract can act as a neuroprotective agent. How, exactly, it does this is not known. However, it is thought to work through a combination of vasodilation (possibly increasing the blood supply to the optic nerve), antiplatelet action (blood thinning), and antioxidant effect.
Evidence that Ginkgo can be used to treat glaucoma:
As far back as 2003 there has been evidence that Ginkgo biloba may have a benefit in the treatment of glaucoma . Patients with Normal Tension Glaucoma (NGT) who were given 40mg of Ginkgo biloba extract three times a day (120mg total daily dose) showed a short-term improvement on their visual fields compared to those who took placebo. No difference in IOP was noted, but the fact that pre-existing visual field defects got better is worth noting.
In late 2013 a study was published in the Journal of Glaucoma evaluating the effect of Ginkgo biloba extract on visual field loss in patients with Normal Tension Glaucoma. These patients were studied for an average of 12 years and were using Ginkgo biloba extract for at least four years. Although there was no effect on intraocular pressure (IOP), there was a significant reduction in the rate of visual field loss in those patients taking Ginkgo biloba extract.
These results are quite impressive as most studies only look at IOP, whereas what we are really interested in is saving vision. This study is unique in that it is (to the best of my knowledge) the only study that has shown that an over-the-counter supplement can effectively reduce the rate of long term vision loss in patients with glaucoma.
Ginkgo Biloba’s Potential Side Effects and Risks:
In a long-term study comparing Ginkgo biloba extract to placebo in the treatment of dementia there were no significant differences in side effects between the two groups. Other studies, however, have noted an association with mild irritability, nausea or diarrhea.
Ginkgo biloba is known to have anticoagulant properties which can result in undesirable bleeding in those who are already taking anticoagulant medications such as aspirin, coumadin, or Plavix. Therefore, I generally do not recommend use of Ginkgo Biloba in my patients who are already taking oral blood thinners. It is important to let all your doctors know if you are taking this supplement. It is also important to discontinue Ginkgo biloba extract prior to any planned surgery.
Ginkgo biloba extract may be found in many dosages. The dosage used in the aforementioned studies ranged from 40mg taken three times daily (120mg total daily dose) to 80mg twice daily (160mg total daily dose).
Cost of Gingko Biloba:
Ginkgo Biloba can be found online, as well as at most pharmacies and health food stores for around $10-60 for a month supply.
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- Quaranta L, Bettelli S, Uva MG, Semeraro F, Turano R, Gandolfo E. Effect of Ginkgo biloba extract on preexisting visual field damage in normal tension glaucoma. Ophthalmology 2003;110:359-62.
- Le Bars PL, Katz MM, Berman N, et al. A placebo-controlled, double-blind, randomized trial of an extract of Ginkgo biloba for dementia. North American Study EGb Group. JAMA 1997;278:132732.
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