But Early Show Medical Correspondent Dr. Emily Senay reports that according to The Journal Of The American Medical Association, researchers have found that ginkgo did not enhance memory or improve cognitive ability like learning or concentration for healthy older adults with normal cognitive skills and no existing cognitive impairment.
The study looked at more than 200 people who took a popular ginkgo supplement for six weeks, which is the time within which the manufacturers claim benefits should appear.
Ginkgo is well advertised and widely available as a desirable ingredient, but not all products containing ginkgo are made with the same purity or dosage. And not all make claims about improving mental ability. The researchers aren't saying that the findings about gingko necessarily apply to every one. But they did single out the brand Ginkoba for testing specifically because it is one of several over-the-counter supplements marketed for its ability to improve memory, attention and other cognitive skills.
There have been smaller studies that show mental improvements for healthy people, and a study that showed slight improvements for people with Alzheimer's. There are those who swear by ginkgo, they point out that this is one single negative study and that more research is needed before we write ginkgo off. They also point out it's an antioxidant that might provide other benefits.
When questioning if the placebo effect could have had an influence on the study, it is important to note that the placebo effect certainly has proven to be very powerful in many studies that have been conducted over the years. A recent study of another natural remedy St. John's Wort showed that the placebo effect was stronger than both St. John's Wort and the drug Zoloft for depression. But in this study the effect of both the placebo and the ginkgo was negligible.