Fruits and Vegetables Cut Stroke Risk
NEW ORLEANS (AP) _ A diet rich in potassium from fruits and vegetables protects arteries from the ravages of high blood pressure and dramatically lowers the risk of stroke, animal studies show.
″You get tremendous protection from strokes by eating more fruits and vegetables,″ Dr. Louis Tobian of the University of Minnesota said Wednesday.
A single extra helping of fruits or vegetables daily might cut stroke risk by as much as 40 percent over an extended period, Tobian said at the American Heart Association’s annual meeting on high blood pressure.
Tobian and his colleague, Tokuichiro Sugimoto, showed in stroke-prone rats that high blood pressure damages the endothelium, a single layer of cells lining arteries in both rats and humans. That damage can lead to obstruction or rupture of arteries.
They also showed that the damage can be almost completely eliminated if rats with high blood pressure are given diets rich in potassium.
Strokes afflict 500,000 Americans each year, killing 155,000 of them, according to the heart association.
Most fruits and vegetables are good sources of potassium, Tobian said in an interview. Among the best are bananas, strawberries, potatoes, and orange and grapefruit juice. Skim milk is another good source, he said.
Since the advent of the modern, junk-food era, Tobian said, American diets have been low in potassium, especially among blacks and young people who may consume a lot of fast food.
″I’m worried about the young singles or marrieds so involved in their careers that they just pick up one junk food after another,″ he said. ″I think there’s going to be a price paid down the line.″
He noted that some studies have shown that bachelors die earlier than married men. He thinks one reason might be that bachelors eat less balanced diets than do married men, and bachelors may therefore be getting an insufficient amount of potassium.
Potassium does not lower blood pressure, Tobian said, but it prevents elevated blood pressure from damaging the arteries.
In the research presented Wednesday, Tobian and Sugkmoto showed that potassium given to rats with high blood pressure can prevent the growth of muscle cells near the inner arterial lining. Such growth narrows arteries and contributes to their blockage by cholesterol and other fatty deposits.
Such blockage in an artery that supplies blood to the brain will cause a stroke. Damage resulting from the abnormal growth of muscle cells can also lead to rupture of arteries, another cause of stroke.
Tobian’s most recent studies are an outgrowth of his long interest in potassium and in the dietary habits of prehistoric human beings.
For several million years before the dietary changes produced by agriculture and the industrial revolution, humans consumed a diet high in potassium, Tobian said.
During that long period, humans evolved in such a way that they came to depend upon that potassium. When diets changed and potassium content dropped, strokes and other forms of heart disease became more prevalent.
Tobian cannot prove that a link exists, but said his research certainly suggests that the dietary change may play a role in the incidence of heart disease.
In one of his first studies of the subject, he gave a group of stroke-prone rats normal diets and compared them with another group of stroke-prone rats given potassium-enryched diets.
Eighty-three percent of the rats on normal diets died of strokes in four months. Among rats given extra potassium, only 2 percent died of strokes in the same period.