Keris KrennHrubec and Diana Zuckerman, PhD

July 2008

Ginkgo biloba has been used in traditional Chinese medicine for thousands of years, and today it is one of the most popular herbal supplements, widely advertised as a beneficial antioxidant that helps prevent memory loss and dementia. Like most herbal products, however, there have been few clinical studies to see if these claims are accurate. Dietary supplements do not have to be evaluated and approved by the Food and Drug Administration (FDA). So how can you know if there are clear benefits, and whether or not they outweigh the risks?

Possible Benefits

New research by Dr. Hiroko Dodge from Oregon State University at Corvallis, suggests that the benefits of ginkgo biloba may be real; however, taking it may also increase the risk of strokes. Dr. Dodge’s research team followed 118 people for three years. These patients were at least 85 years old, healthy, and did not have any signs of memory loss or dementia when the study started. Half of these people took ginkgo biloba, and the other half took a placebo. Throughout the study, a patient’s memory was evaluated using a 5-point scale called the Clinical Dementia Scale, which is commonly used by doctors and researchers to test memory impairment. At the end of the three years, 21 people had developed memory problems or dementia according to this scale. Of these 21 people, 14 had taken the placebo pills, and 7 had taken ginkgo biloba. Since fewer of the people who developed memory problems were taking ginkgo biloba, these findings show a trend that taking it may help delay or prevent the onset of dementia in aging patients. However, the trend was not statistically significant, and therefore could have arisen because of chance.

The researchers also did another analysis of their data, just looking at the patients who consistently took their ginkgo biloba on a regular basis. The patients taking ginkgo biloba regularly had a 70% lower risk of developing dementia problems. Although more impressive, this difference was stilly not statistically significant.

Possible Risks

Unfortunately, by the end of the three years, seven of the patients taking ginkgo biloba had strokes, while no patients taking the placebo did. Even though this finding also could have arisen due to chance, it does raise some concern among scientists. Previous research has shown that gingko biloba can increase circulation and reduce the blood’s ability to clot. However, strokes are caused by blood clots, which seems to contradict the expected benefits. A larger study would be necessary to find out if this apparent benefit and risk are real.

Should I take Ginkgo Biloba?

Like most herbal products, nobody knows exactly how ginkgo biloba works. Most people in the medical community agree that it increases blood flow. This effect is good for some people, like those at risk for blood clots, but it can be bad for other people who have bleeding problems or who are already on blood thinners. For this reason it is very important to talk to your health care provider before starting to take ginkgo biloba or any other herbal product to make sure that it does not interfere with any medications you are already taking.

Is ginkgo biloba good or bad for you? Even with this new research, we just don’t know. However, this research shows that there are important reasons to study this supplement. Many people already take ginkgo biloba, it is important to know how much the supplement is helping them – or if it is harmful.

Reference

Dodge, Hiroko, et al. (2008). A randomized placebo-controlled trial of ginkgo biloba for the prevention of cognitive decline. Neurology.