Ginkgo biloba is taken by millions of people. As with many other organic plant extracts, anecdotal health claims abound for ginkgo. Many people think of it as a general tonic and consider memory enhancement as a sidelight. Others call it a fad that they wouldn't touch with a pole of any size. But what are the facts? What do we really know about ginkgo biloba?
Ginkgo contains many organic substances, which include flavonoids, terpenoids such as ginkgolides and bilobalide, and several acids. These ingredients have varying degrees of antioxidant activity, and this effect may underlie their promemory action.
Nearly all the early studies that evaluated ginkgo biloba as a treatment for dementia came from Europe, and most did not employ rigorous research methodology. Then a North American consortium published a study in the Journal of the American Medical Association, utilizing EGb 761, an extract of ginkgo biloba marketed by a German company that provided the financial support for the experiment. In that study, of the 309 patients with dementia who were randomized to receive EGb 761 or placebo, only 78 patients on EGb and 59 patients on placebo were able to complete the one-year study. The EGb 761 study's results: even though the clinicians found no difference in their global impression between patients on ginkgo and placebo, patients on ginkgo showed significantly less decline on both a standard cognitive test and a forty-nine-item rating instrument completed by the caregiver (usually a family member). The test scores indicated that over the one-year study's duration, the ginkgo group held its own, with no cognitive deterioration. In contrast, the placebo group worsened appreciably. The magnitude of the effect was small (2 to 3 percent advantage for ginkgo over placebo on a cognitive test), which is probably why the clinicians' global impression showed no difference between the ginkgo and placebo groups. These findings are consistent with an earlier, less rigorous, study of 222 outpatients with dementia that showed 23 percent of patients improving on ginkgo biloba compared to 10 percent on placebo.
In the EGb 761 study, other than a slight increase in stomach complaints, ginkgo's side-effect profile was essentially identical to placebo. But as with every medication, alternative or otherwise, ginkgo is not totally devoid of side effects. It has anticoagulant (anticlotting) properties that increase the risk of bleeding in the presence of other anticoagulant medications, particularly warfarin (Coumadin), which is commonly prescribed for people at high risk for heart attack or stroke. A few such cases of complications due to excessive bleeding have been reported in the medical literature.
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