Salt Sensitivity Lowered with Exercise

Excessive intake of salt causes high blood pressure in some, but not all, people. High blood pressure increases risk for heart attacks, strokes, and kidney damage. Why do some people develop high blood pressure when they take in a lot of salt, while others do not? A recent study from the University of Minnesota shows that middle-aged people who start an exercise program lose their tendency to develop high blood pressure when they take in extra salt (Journal of Human Hypertension, May 2006).

All people who exercise frequently and hard need to take in extra salt. During World War II, Dr. James Gamble of Harvard Medical School showed that the only mineral that exercisers need in large quantities is salt. If heavy exercisers don’t take in enough salt, they will eventually run low on salt and suffer fatigue, muscle aches and cramps, and be at increased risk for injuring themselves.

The Minnesota study measured blood pressure in people when they followed a high-salt diet and again when they went on a low-salt diet. The salt-sensitive people who developed high blood pressure on a high-salt diet were started on an exercise program. After six months, many of these people did not develop high blood pressure when they again ate a high-salt diet. This shows that regular exercise can control high blood pressure caused by a high-salt diet. Previous studies show that it is very bad advice to tell most exercisers to restrict their intake of salt. This new study shows that many people who develop high blood pressure from a high salt diet when they are sedentary, will not develop high blood pressure on the same diet when they exercise.