Leaf extracts from one of the world's oldest trees, the ginkgo, can be found in breakfast cereal, tea and tablets sold at supermarkets and health food stores. Marketers claim it can help your memory, but scientists don't agree on whether the herbal product can actually give your brain a boost.
Researchers have been studying ginkgo as a potential "smart drug" for healthy people. They want to know if it improves memory skills or slows the deterioration of mental skills among people with mild cognitive impairment or Alzheimer's disease. They're also interested in whether it can prevent disease altogether.
Last week, a study in the Journal of the American Medical Assn. raised new questions about benefits for healthy people. Researchers found that a common brand of ginkgo did nothing to sharpen memory, concentration or learning in healthy elderly volunteers--a blow to the claims of some supplement companies that ginkgo can "enhance" focus and improve memory in just weeks.
But that's hardly the last word about a popular supplement with annual worldwide sales of more than $500 million. The study was sharply criticized by the supplement industry and some health professionals, who contended that other U.S. and foreign studies have demonstrated positive effects.
The study compared more than 100 elderly volunteers who took 120 milligrams of ginkgo a day to a similar number of volunteers who took a dummy pill. Neither the subjects nor researchers knew who got the ginkgo. After six weeks, those who took the product, Ginkoba, scored no better on 14 different tests of mental ability than the placebo group.
Steven H. Ferris, executive director of the Silberstein Institute for Aging and Dementia at New York University, praised the study, saying it realistically demonstrated the experience of people who might purchase ginkgo and follow the label instructions.
Some proponents of ginkgo criticized the study. Los Angeles psychiatrist Hyla Cass, who often recommends ginkgo to patients because of its potential antioxidant effects on the heart and brain, said study subjects should have been given higher doses for longer periods.
However, researchers selected the dosage based on manufacturer instructions and recommendations from Germany's Commission E, a regulatory agency that reviews the effectiveness of herbal medicines, said the study's lead author Paul R. Solomon, who also wanted to test the manufacturer's claim of results in four weeks.
