American researchers found during a three-year study not only that the alleged memory enhancing properties of ginkgo biloba were questionable, but that it seemed to pose a certain health risk.

Researchers with the Oregon State University conducted a three-year study on the effects of ginkgo biloba in octogenarians. The herbal supplement said to enhance memory did not indubitably offer protection against memory loss in octogenarians, the authors wrote in a study published in the February 27 online issue of Neurology, the medical journal of the American Academy of Neurology.

MedicalNewsToday.com reports that 118 people age 85 and older with no memory problems participated in the study. Half of the participants took ginkgo biloba extract three times a day and half took a placebo.

During those three years, the numeric difference between participants taking the extract and those taking the placebo that developed memory problems, or questionable dementia, was not significant, the researchers said.

Another development they noticed though was of significance: participants who followed directions and took the extract regularly throughout the study had a 68 percent lower risk of developing mild memory problems than those who took the placebo. Larger studies are necessary though to establish whether the ginkgo biloba extract indeed was effective.

Study author Dr. Hiroko Dodge, of the Department of Public Health and Center for Healthy Aging Research at Oregon State University in Corvallis and colleagues, warn about one particular tendency they noticed during the study. People taking ginkgo biloba appeared to be more likely to have a stroke or mini stroke.

He noted that while further research is needed for an unambiguous conclusion on the effects of the herbal supplement, its wide availability, inexpensiveness and wide use among people pose questions regarding its safety.

Some studies have found that the herb may help some people with Alzheimer's disease but, again, further research is needed to find the exact way in which it works.