BAKERSFIELD, Calif. -- Preliminary research into ginko and heart disease looked so promising: some studies suggested the herbal supplement had antioxidant properties, while others showed it might reduce blood clotting.

But taking daily gingko does not appear to affect the rate of actual heart problems, according to new research from the University of Pittsburgh.

Doctors studied more than 3,000 people over the age of 75 years who were assigned to take either gingko or a placebo two times a day.

Results showed no differences in the rate of heart attacks, strokes, or death from heart disease between the two groups.

However, narrowing of the blood vessels in the legs and feet -- a condition called peripheral vascular disease or PVD -- was about twice as common in the placebo group.

People with serious vascular disease often need surgery or even amputation to correct the problem.

In Europe, gingko is already used to fight peripheral vascular disease, but researchers said more study is needed to confirm the effects and to determine the ideal dose of gingko in reducing PVD.