DALLAS (American Heart Association) -- Linoleic acid - found in vegetable oils and soybeans - appears to protect against strokes, researchers report in the August issue of Stroke: Journal of the American Heart Association.

Linoleic acid is an important essential fatty acid found in corn, sunflower oil, safflower oil, and soybeans. Fatty acids help control blood pressure, blood clotting, inflammation and other body functions. Linoleic acid also tends to lower blood cholesterol.

Researchers believe linoleic acid may reduce the risk of ischemic stroke (stroke caused by blood clots) because it can lower blood pressure and improve circulation in small blood vessels, says lead author Hiroyasu Iso, M.D. Ph.D., M.P.H., professor, Department of Public Health Medicine, Institute of Community Medicine, University of Tsukuba, Ibaraki-ken, Japan.

The researchers examined frozen blood samples from 7,450 Japanese men and women, aged 40 to 85 years. The surveyed population had participated in cardiovascular risk surveys between 1984 and 1993 in Japan. Researchers identified 197 strokes - 122 ischemic, 75 hemorrhagic - that occurred within this group.

Linoleic acid consumption ranged from 9.5 to 13.3 grams per day, researchers note.

They found that a 5 percent increase of linoleic acid was associated with a 28 percent reduction in total stroke risk; a 34 percent reduction in ischemic stroke, 37 percent reduction in lacunar infarction (strokes involving the many small arteries that supply the deeper parts of the brain) and 19 percent reduction in hemorrhagic stroke (caused by bleeding).

"When we adjusted for other fatty acids, these associations become weak, but the association between linoleic acid and the stroke risk persisted," says Iso.

A potential hazard of consuming more linoleic acid was not tested. The authors say that a clinical trial is necessary to confirm the causality between linoleic acid intake and risk of ischemic stroke.