Ginkgo Risk Raises Concern

Past studies have questioned the touted benefits of the popular herbal remedy ginkgo biloba.

Now some German researchers say sales of the product should be restricted because it may increase risk of seizure among people with epilepsy and reduce effectiveness of antiseizure drugs.

"It is therefore important that the large number of ginkgo biloba product users and their health care providers be made aware of these risks, in order to enable them to make informed decisions," University of Bonn researchers Eckhard Leistner and Christel Drewke say in a statement. Their paper is published in the Journal of Natural Products.

The researchers compared data from past studies and found 10 cases of seizures in epileptic patients using the supplement. The reaction is caused by a toxin in ginkgo, they say.

Mental sharpness and improved memory are two of the common benefits manufacturers cite to market their products. However, past studies have questioned these claims. Because herbal supplements are not regulated as a drug by the Food and Drug Administration, companies are allowed to make claims without backing up the science. A study last year disputed claims that ginkgo helped Alzheimer's patients.

Used by the Chinese for hundreds of years, ginkgo biloba is sold by numerous supplement makers like Nature's Way Products and can be found everywhere from Wal-Mart to Amazon.com. Ginkgo sales dropped 8 percent in 2008 to $99 million, according to Nutrition Business Journal.