点击显示 收起
Nov. 24, 2009 -- Ginkgo biloba, a popular herbal supplement, doesn’t prevent cardiovascular death or major events such as stroke and heart attack in people 75 and older, a new study shows.
However, the herb may have some benefit for people with peripheral vascular disease, scientists say in the Nov. 24 issue of Circulation: Cardiovascular Quality and Outcomes.
Further study is needed to support the new evidence that the herb may help people with peripheral vascular disease, researchers say. Peripheral vascular disease involves poor circulation of blood vessels outside the brain and heart. Classic symptoms include pain in the lower legs, typically associated with walking.
Ginkgo biloba has been used for the treatment of peripheral vascular disease in Europe. The researchers note that some studies have suggested that Ginkgo biloba can help increase walking distance before the onset of leg pain related to peripheral vascular disease.
Researchers randomly assigned 3,069 people age 75 and older to a placebo or 120 milligrams of Ginkgo biloba extract taken twice daily. They followed the participants for an average of six years. The main purpose of the original study was to evaluate the effect of the supplement on the development of dementia. No effect on dementia was found. The current findings come from additional analysis from the original study.
During the study period, 355 people died, 87 as a result of coronary heart disease, and there was no significant difference between patients taking Ginkgo biloba or the placebo. The researchers also say there were no differences in the incidents of heart attack or stroke.
Of the 355 patients who died, 197 were in the Ginkgo biloba group, and 188 in the placebo group, the researchers say.
Although there were only 35 peripheral vascular disease events, the researchers detected a possible benefit for those taking Ginkgo biloba.
Lewis H. Kuller, MD, DrPH, of the University of Pittsburgh tells WebMD that a peripheral vascular disease event "means something like amputation, or a major surgical procedure in lower extremities" such as a bypass procedure.
"This is not just people who had pain when they walked or were put on medication because their feet were cold," he says. "These were major surgical events. The numbers are small but they are very solid."
Twelve people taking the herb in the study had peripheral vascular disease events - compared to nearly twice that number, 23, in the placebo group.
“The difference between [Ginkgo biloba] and placebo was significant but based on very small numbers,” the researchers write. “The results are consistent with studies in Europe that reported increased walking time or distance without pain in trials of [Ginkgo biloba] versus placebo” among patients with peripheral vascular disease.
“It is possible that [Ginkgo biloba] has a unique effect on [peripheral vascular disease] by increasing blood flow...”
What is now needed, the researchers write, is a larger clinical trial. They say their findings aren’t sufficient to call for the use of Ginkgo biloba by people at increased risk for peripheral vascular disease, which can be a precursor of strokes and heart attacks.