Diet restores youth to aging vessels.

Diet restores youth to aging vessels

To maintain normal blood pressure, blood vessels must dilate and constrict. Receptors on the vessel walls appear to control these crucial functions, and scientists have postulated that hypertension results when the receptors controlling constriction work well but the dilation receptors fail to relax the vessel. As people age, their vessels lose some dilating ability. But new findings indicate a low-salt diet can restore lost vessel dilation in older people, possibly lowering their risk of hypertension.

Ross D. Feldman and Christine Sinkey of the University of Iowa in Iowa City studied 10 people aged 48 to 72 and eight others aged 20 to 31, all of whom had normal blood pressure. Volunteers ate a high-salt diet for four days. On the fifth day, scientists injected each subject with a localized microdose of a substance that causes vessel contriction, followed by a small dose of isoproterenol, an adrenaline-like substance that causes dilation. They found that blood vessels in older subjects dilated only half as much as those in younger subjects.

After the researchers gave the group a low-salt diet for four days, the blood vessels of older subjects dilated as much as those of young subjects. These results suggest older people can stave off an age-associated malfunction in their blood vessel receptors--and reduce their risk of hypertension--by reducing dietary salt, says Feldman, now at the University of Western Ontario in London, Ontario.