Lowering Sodium May Be Counterproductive

Reducing salt intake could be counterproductive at least for healthy adults. That’s the conclusion of a new European study involving careful measurement of sodium balance. For decades, public health officials have been urging Americans to eat less salt to lower their blood pressure and reduce their likelihood of suffering a deadly heart attack or stroke. The study published in the Journal of the American Medical Association has created a firestorm of controversy.
The investigators recruited more than 3500 healthy adults from Belgium and other countries. Salt intake was assessed by analyzing 24-hour urinary sodium levels. This is a far more accurate way of determining sodium intake than dietary recall. Eight years later the participants had their blood pressure and urinary sodium measured again. Data from people who had died or suffered non-fatal heart attacks and strokes during the course of the study were carefully analyzed.
The investigators found that systolic blood pressure increased modestly with high salt consumption. Diastolic blood pressure was unaffected and there was no relationship between salt intake and a diagnosis of hypertension in these healthy individuals. More surprisingly, though, the people who consumed the lowest amount of salt had the greatest risk of death from cardiovascular complications. The authors concluded that urging otherwise healthy individuals to cut back on salt to prevent high blood pressure or heart disease is not supported by the evidence.
The results do not apply to those with existing heart disease or hypertension or people who are known to be salt sensitive. Public health authorities have reacted with horror to the new study. They have been advising all Americans to reduce sodium intake for decades. No doubt there will be tremendous debate about these findings over the coming months and years.
[JAMA, May 4, 2011]