JUST THE FACTS
Salt and High Blood Pressure

by Jeff Novick, M.S, R.D.

Both exercise and a low salt diet have been recommended for lowering blood pressure. But the results of a study that appeared in the Journal of the American College of Cardiology indicate that restricting dietary sodium may be the more important of the two. Blood pressure is recorded as two numbers-the systolic pressure, as the heart contracts, and the diastolic pressure, as the heart relaxes between beats. According to researchers, as the stiffness of the major arteries increases with age, so can systolic pressure-which is given as the first number in a blood pressure reading.

In the study, investigators assigned thirty-five postmenopausal women with moderately high systolic blood pressure to take one of two measures: walk three to four days per week for thirty minutes per day, or restrict their dietary sodium intake to less than 2.4 grams of sodium per day without changing their total calorie intake. (One teaspoon of salt has 2200mgs of sodium chloride) Dr. Douglas R Seals and colleagues at the University of Colorado Health Sciences Center in Denver report that after three months women in both groups saw their blood pressure fall, but the reductions were three-to fourfold greater in women who restricted their salt intake compared with those who walked.

For instance, the average drop in systolic pressure for women who cut their salt intake was about 16 mm Hg, compared with 5 mm Hg among those who exercised. Blood pressure that consistantly stands at 140/90 mm Hg or above is considered high. Women in the study had systolic pressures ranging up to 159 mm Hg. The results came as a suprise to Seals. "We expected regular aerobic exercise to produce simular or perhaps even greater reductions in blood pressure compared with moderate dietary sodium restriction. Instead, exercise did lower blood pressure, but the reductions with sodium restriction were much greater". Seals also said that postmenopausal women will have the greatest impact on their blood pressure if they combine changes in diet with an exercise program, and lose weight if they need to.

"It is important to emphasize the risk of disease associated with elevated systolic blood pressure for postmenopausal women, and actually middle-aged and older adults in general," he noted "Only a few years ago it was believed that the diastolic blood pressure was the most important to control from the standpoint of predicting risk of future heart disease. We now know that in this population, elevated systolic blood pressure is the single most important risk factor for future development of heart disease."

To lower dietary sodium, Seals advises people to refrain from adding salt to food, stay away from processed foods high in sodium, and eat lots of fruits and vegetables. Keep in mind that doctors like Joel Fuhrman, M.D. and those of the Pritkin Longevity Center recommend that patients ingest even lower levels of sodium. Dr. Fuhrman tells his patients never to add salt to a food. As a result, his patients' daily intake of sodium is less than half the 2.4 grams recommended in the study. The benefits of this approach are dramatically better.