For decades Americans have been told that a low sodium diet is essential to warding off hypertension. Yet a new study conducted in Belgium suggests that a low salt diet actually increases the risk of heart attacks and strokes while doing nothing to prevent high blood pressure. Federal scientists have discredited the Belgian salt study, saying that researchers were led to erroneous assumptions by a flawed methodology.
High blood pressure, or hypertension, eventually affects about 90 percent of Americans, according to the American Heart Association. The AMA recommends that you limit your sodium intake to no more than 1.500 milligrams a day—less than half the current intake of most Americans– to reduce the risk of high blood pressure, heart attacks, stroke and kidney disease. But the Belgian salt study raises questions about the benefits of a low-salt diet.
Is a low sodium diet helpful or harmful?
In the Belgian salt study, published in a recent edition of the Journal of the American Medical Association, researchers tracked 3,681 people averaging age 40 for nearly eight years. None had high blood pressure at the start. They found that those who consumed less sodium had slightly lower blood pressure, but an increased risk of death from heart disease. Fifty people in the lowest sodium intake group died during the study, compared with 24 in the middle sodium group and just 10 in the high sodium group. The high sodium group had a slight increase in blood pressure, but they were no more likely to develop hypertension than the lowest sodium group.
50 people in the lowest third of salt consumption (2.5 grams of sodium per day) died during the study as compared with 24 in the medium group (3.9 grams of sodium per day) and 10 in the highest salt consumption group (6.0 grams of sodium per day). The researchers speculate that sodium intake low enough to decrease blood pressure may also decrease sensitivity to insulin, encourage a stress response in the nervous system, and affect hormones that regulate blood pressure and sodium absorption.
Low salt diets may not be healthy for everybody
Jan Staessen, a professor of medicine at the University of Leuven in Belgium said the study does not support recommending reduced salt intake for everyone across the board. Less salt could be beneficial in lowering the blood pressure of people with hypertension, but recommending it to the population as a whole hasn’t been proven to be completely safe. The Centers for Disease Control strenuously disagrees. Dr. Peter Briss of the CDC told the New York Times that the study was small; that its subjects were relatively young and that with few cardiovascular events, any conclusions to be drawn are suspect. Briss said the researchers’ conclusions contradict a body of evidence showing higher sodium intake can increase the risk of cardiovascular disease.
The challenge of a low-salt diet
Despite the Belgian salt study’s shortcomings, the findings can be interpreted as suggesting that sodium guidelines take into account differences among individuals. Researchers examined a relatively young, mostly white population. Outside the laboratory, blood pressure tends to rise with age and affect African-Americans, older people and overweight people more. Dr. Michael Alderman, editor of the American Journal of Hypertension, says that all salt studies are flawed, because the recommended sodium intake of 1,500 milligrams a day is impossible to achieve in this day and age. The only way that will ever happen is if food manufacturers change the way they prepare their products, which considering the expense involved and the salty preferences of the general public, isn’t going to happen anytime soon.
Source: New York Times, CNN, USA Today