CHICAGO -- A new study suggests gingko supplements do nothing to quickly improve memory in healthy people, a finding that goes against years of well-publicized claims that helped turn the supplements into a multimillion-dollar industry.
The over-the-counter supplements are made using extract from the fan-shaped leaves of the gingko biloba tree.
Early studies suggested the supplements could boost mental function in people with and without mild dementia, however, those studies had methodological flaws and were too short to measure a true effect, according to the authors of the new study.
The new study, reported in Wednesday's Journal of the American Medical Association, involved 230 people over age 60 who had no signs of memory impairment and found that the gingko supplements worked no better to improve memory than dummy pills over a six-week period. Some of the supplements are advertised to have a noticeable benefit in four weeks.
"We don't see any benefit," said lead author Paul Solomon, a psychology professor at Williams College.
Solomon said his study involved the same type of rigorous testing required by the Food and Drug Administration for pharmaceutical drugs, though supplements like gingko are not FDA-regulated. The same battery of mental tests was given at the beginning and end of the study.
While both groups' scores improved slightly, that likely was because they'd taken the tests before, and the placebo and gingko patients performed equally well the second time around, Solomon said.
Gingko has been thought to improve blood flow to small veins and capillaries, ostensibly helping deliver oxygen to the brain. It also contains antioxidants, substances that absorb chemicals called free radicals produced during metabolism that are thought to damage cells.
Dr. Steven DeKosky, chairman of the University of Pittsburgh's neurology department, said the study doesn't address whether larger doses taken for a longer duration or taken by people who already have memory problems would be beneficial.
DeKosky is the lead researcher in a government-funded study examining whether gingko in doses equal or double those in the JAMA study can help prevent Alzheimer's disease. Participants in his study are older than 75, have normal mental function or slight memory problems and are taking gingko for five years.
Solomon said it's possible gingko pills would show some mental benefits in healthy people if taken longer than six weeks, the study's duration. But he noted that the tablets used in the study, Pharmaton Natural Health Products' Ginkoba, are marketed as producing noticeable benefits after just four weeks at the study's dose, 120 milligrams daily.
Pharmaton's David Morrison said the findings are from a single study that doesn't "negate the vast body of evidence showing that gingko biloba is effective."
On the Net: