Taking the herbal supplement ginkgo biloba may increase the risk of having a stroke, according to a study published online on Wednesday.
It may however also help delay the onset of cognitive impairment in normal elderly adults.
Extracts of ginkgo biloba are among the most widely used dietary supplements. The herb is marketed as a memory enhancer, and some studies have suggested it may help improve memory and other mental functions in people with dementia.
"One of the most pressing public health problems facing our society is the rapidly growing number of people who, due to their age alone, are at high risk of developing dementia. The potential to delay or prevent this is of great importance," study chief Dr Hiroko H. Dodge, from the Oregon State University in Corvallis, said in a statement.
The three-year study involved 118 people age 85 and older with no memory problems. Half of them took ginkgo biloba extract three times a day and half took a placebo.
During the study, 21 people developed mild memory problems, or questionable dementia: 14 of those took the placebo and 7 of those who took the ginkgo extract. Although there was a trend favouring ginkgo, the difference between those who took ginkgo and those who took placebo was not statistically significant.
68% lower risk
However, when the researchers took into account whether people followed directions in taking the study pills, they found that people who reliably took ginkgo had a 68 percent lower risk of developing mild memory problems than those who took the placebo.
"These results need to be clarified with larger studies, but the findings are interesting because ginkgo biloba is already widely used, readily available, and relatively inexpensive," Dodge said.
Ginkgo tied to strokes
As noted, more strokes and mini-strokes were seen in the ginkgo group. Seven people taking ginkgo had strokes, while none of those taking placebo did. "Ginkgo has been reported to cause bleeding-related complications, but the strokes in this case were due to blood clots, not excessive bleeding, and were generally not severe," Dodge noted in a statement.
"Further studies are needed to determine whether ginkgo biloba has any benefits in preventing cognitive decline and whether it is safe," he added.
SOURCE: Neurology, online February 27, 2008. – (Reuters Health)
Natural not always safe