Vegetable Fats Figure into Reduced Stroke Risk

Source: Tufts University
September 18, 2002 (Reviewed: September 3, 2004)

Can a "heart-healthy" diet help protect you from having a debilitating stroke? Very likely, yes, but scientists continue to work on the details of how different types of dietary fats help or hurt the health of blood vessels, including those that supply blood to the brain. Information from a recent study published in the journal Stroke has associated high blood levels of polyunsaturated fatty acids with a reduced risk of the commonest form of stroke - ischemic stroke - in which there's a blockage of blood flow to a part of the brain, usually due to thrombosis in a brain artery.

Dietary factors found to make a difference

For this analysis, Japanese researchers identified 197 participants in a cardiovascular study who had suffered a stroke at some point during the study. They then recruited another 591 healthy participants, matched for gender, age, and community, to serve as a control, or comparison group. Blood samples collected during the study were used to measure levels of different types of fats in the bloodstream. The researchers were looking for a connection between blood fats and the risk of having a stroke.

They found that a high blood level of linoleic acid, a polyunsaturated fatty acid found in vegetable oils, was associated with a reduced risk of ischemic stroke.

How it might work

The scientists offer several possible explanations for their findings. Linoleic acid reduces the stickiness of blood cells, making them less likely to clump together and block an artery. This type of fatty acid also seems to help keep red blood cells healthy so that they can carry oxygen more efficiently throughout the body. There is also some evidence that linoleic acid may help lower cholesterol levels, improve blood glucose levels, and help regulate blood pressure, all of which would make a stroke less likely.

The benefits of vegetable fats

The authors of the study emphasize that strokes result from many factors, and it is too early to tell to what degree diet was responsible for the results seen in this study. But they are encouraged by the fact that high blood levels of a fatty acid found in vegetable oil seemed to help many of the study participants stay healthy.

In fact, heart health nutrition guidelines already encourage a diet that emphasizes the polyunsaturated fats in vegetable oils and limits foods high in saturated fats. Food manufacturers undo some of the health benefits of polyunsaturated fats when they harden them to make trans fatty acids for use in solid margarine and shortening. The best thing is to use vegetable oil in its natural, liquid form whenever possible. If you do use margarine, choose a liquid or soft variety.

Source

• Linoleic acid, other fatty acids, and the risk of stroke. H. Iso, S. Shinichi, U. Umemura,  et al., Stroke, 2002, vol. 33, pp. 2086--2093

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