Reducing dietary salt in the US could save thousands of lives each year and prevent even more MIs and strokes, according to a new study in the New England Journal of Medicine. But at least one critic, hypertension expert Michael Alderman, maintains the data are not sufficient to justify a large-scale change in public policy.

Kirsten Bibbins-Domingo and colleagues estimated the benefits of reducing dietary salt in the US diet by 3 g per day. According to their calculations, such a reduction each year would reduce the number of strokes by 32,000 to 66,000, MI by 54,000 to 99,000, and deaths from any cause by 44,000 to 92,000. They write that all parts of the population would derive benefit, though blacks would benefit most and women would benefit particularly from the reduction in strokes. The beneficial effects of salt reduction are “on par with the benefits of population-wide reductions in tobacco use, obesity, and cholesterol levels.”

In an accompanying editorial, Lawrence Appel and Cheryl Anderson write that “the evidence supporting the call to reduce salt intake as a means of preventing cardiovascular disease is compelling” and say that the US “lags behind many countries when it comes to translating this research into policies that achieve meaningful reductions in dietary salt.” They call for lawmakers “to swiftly implement public health interventions that result in population-wide reductions in salt intake.”

Michael Alderman told CardioBrief that the “modeling exercise… assumes that the blood pressure effect shown in antihypertensive trials, and observed in epidemiological studies, based upon what the BP fall achieved in relatively short term sodium reduction studies, will all translate into massive reductions in mortality and morbidity. Unfortunately, it is based upon a deeply flawed assumption that has not been tested in randomized clinical trials. The hypothesis is that only the BP effect, not the other effects of reduced salt– increased sympathetic nerve activity, increased resistance to insulin, increased aldosterone secretion, and activation of the renin-angiotensin system– would affect morbidity and mortality. Maybe, but usually, when an intervention has multiple effects, before applying, it is safest to do randomized clinical trials with health outcomes as endpoints. We don’t have that for salt reduction. Instead, the experiment we seem to be seeking is to have the whole population lower their salt intake with the hope that they are right. History suggests this to be a risky business– sometimes with bad results. In 1980 the national dietary recommendations said to reduce total fat. In 2000, they reversed that, saying by encouraging increased carbohydrate intake, they may have contributed to an epidemic of obesity and diabetes.”

Alderman cited other “examples of unintended consequences,”such as trans fats and postmenopausal hormone replacement, and lamented that the NEJM authors “don’t even note the serious scientific questions raised by skeptics.”