Satu Helske of the Wihuri Research Institute in Helsinki, Finland, said plant sterols can block the absorption of dietary cholesterol into the body and high vegetable diets.

Researchers collected blood samples from 82 patients with severe aortic valve stenosis -- abnormal narrowing -- and aortic valves from 21 individuals undergoing valve surgery, along with respective controls. They observed that non-cholesterol sterols, including plant sterols, can accumulate in aortic valves.

Aortic valve stenosis results from cholesterol accumulation in the valve between the left ventricle and aorta; this impedes the flow of blood and puts extra pressure on the heart. About 2 percent of individuals over age 65 -- and more than 5 percent of those over 85 -- have aortic valve stenosis, researchers said.

The finding, published in the Journal of Lipid Research, suggests that beneficial plant sterols may end up becoming a risk factor for aortic valve stenosis but there is a need to conduct more studies, such as whether dietary sterols and sterol supplements produce different effects.