Study: Salt raises risk of heart disease for many

WASHINGTON (Reuters) -- Even people with normal or low blood pressure have a higher risk of heart disease if they are sensitive to salt, researchers said Wednesday.

A review of a 17-year-old study showed that people whose blood pressure fell when they went on a low-salt diet were more likely to live longer -- even if they had normal blood pressure to start with.

The study suggests that most people should watch their salt intake, regardless of their blood pressure, Dr. Myron Weinberger, professor of medicine and director of the Hypertension Research Center at the Indiana University School of Medicine, said in an interview.

"We know that just a modest decrease in salt intake is not harmful and does not require the purchase of special food," Weinberger said.

"We believe that if you reduce your salt intake, it may prevent or delay heart disease."

Doctors have long known that reducing salt can help people with high blood pressure, defined as being anything higher than 140/90. Studies show that about a quarter of the general population and about 60 percent of people with high blood pressure are sensitive to salt -- meaning that their blood pressure drops significantly if they go on a low-salt diet.

Weinberger and colleagues started out with a small study of some people who had taken part in a blood pressure study years earlier. To their surprise, they found that the people who started out as salt-sensitive had an eightfold increase in blood pressure over a 10-year period.

So they went back to a larger study they had done of 708 people in the early 1970s. They had assumed 27 years ago that the people in that original study who were sensitive to salt but who had normal blood pressure would be all right.

But they were not. They found 600 of the original 708 people. "We found that 120 of them had died," Weinberger said.

The salt-sensitive people were more likely to have died, both of heart disease and of all causes.

"We also found that the survival rate of salt-sensitive people with normal blood pressure is no better than people with hypertension," he added. "We are hoping to find out why."

Weinberger, who presented his findings to the a conference of the American Heart Association's Council for High Blood Pressure Research being held in Washington, has some ideas.

It could be the salt-sensitive people had their blood pressure go up over time. Salt sensitivity was also associated with a tendency to kidney disease and diabetes, as well as with left ventricular hypertrophy, a heart condition.

His team is now looking at 275 people from the study who are still alive to see if the salt-sensitive ones have higher blood pressure, kidney disease, diabetes or the heart condition.

In the meantime, it is hard for the general public to know if they are at risk.

"How do you tell if you are salt-sensitive?" Weinberger asked. "There is no easy test." He noted that studies have suggested there may be a gene or genes that are associated with salt sensitivity, so people may be able to have a quick genetic check one day.

African-Americans are also more likely to be salt sensitive.

"Doctors say this is interesting but useless information," Weinberger added. But he said it might not be hard to put someone on a low-salt diet for a week or 10 days and see if their blood pressure responds. "I need to make a plea that people should not do this on their own," he added.

Copyright 2000 Reuters. All rights reserved. This material may not be published, broadcast, rewritten, or redistributed.

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