Second controlled trial of low-sodium diet confirms health risk

It remains hard to believe, when the daily newspapers are screaming for action to curtail population sodium intakes, that until this month, only one controlled trial has ever examined the actual health outcomes of salt reduction. Sure, we've seen computer models based solely on blood pressure projections that predict fewer heart attacks and lower cardiovascular mortality. But this fantasy has been "mugged by reality" as the data begin to appear in the peer-reviewed literature.

This month's Clinical Journal of the American Society of Nephrology published the results of the second controlled trial of low salt diets. Like the first, this was done in a group of high-risk patients. The first study found low-salt diets caused more hospitalizations and greater mortality among congestive heart failure patients. This new study, by a Chinese research team headed by Dr. Jie Dong, "Low dietary sodium intake increases the death risk in peritoneal dialysis." It's conclusion:

This study revealed that low dietary sodium intake independently predicts the high overall and cardiovascular mortality in dialysis patients.

The researchers suggested a J-shaped curve as described by Dr. Michael H. Alderman in his presidential address to the International Society of Hypertension. Dong et al termed it "another example of 'reversal epidemiologic phenomenon," continuing:

In the case of dialysis patients, harm may outweigh benefit ... Low sodium intake is significantly related to overall and CVD mortality. Sodium restriction did generate undesirable effects in previous studies including increased insulin resistance, activation of the renin-angiotensin system and increased sympathetic nerve activity. ... We reveal for the first time that low sodium intake is not necessarily a good thing....