Gabe Mirkin, M.D.
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.
Checked 3/1/08