A paper in the New England Journal of Medicine, Projected Effect of Dietary Salt Reductions on Future Cardiovascular Disease, concludes that “Modest reductions in dietary salt could substantially reduce cardiovascular events and medical costs and should be a public health target.” This conclusion is based on the use of a very complicated computer model of coronary heart disease. It extrapolates from this model to the population at large, ie, those without heart disease, and reaches a conclusion that everyone would benefit from dietary salt reduction.
It further posits that “Reducing dietary salt lowers…the risk of cardiovascular disease. Here’s the reference the authors of the study cite to support this conclusion. Effect of longer-term modest salt reduction on blood pressure. As you can see there’s nothing in this paper to support this conclusion other than speculation that such a result should follow reduced dietary salt. There are no data in the paper to support this view. The view may be correct, but this reference doesn’t show it’s so. Basically, what the authors assume is that healthy subjects will sicken from a salt intake greater than about 100 mmoles/day and that the higher salt intake goes the greater the resultant ill health. Their health will degrade goes the argument because they will develop hypertension.
It has been clear for decades that part of the population is salt sensitive. Such people have substantial increases in blood pressure as dietary salt increases. The subsequent hypertension they may develop is a major cause of stroke and cardiovascular disease. They would be much better off to reduce their salt intake. Likewise, patients with heart, kidney, and liver disease would also benefit from reduced salt intake. But we also know that a significant part of the population is salt insensitive. Despite large intakes of salt these lucky individuals do not increase their blood pressure or suffer deleterious effects from large salt intakes.
The authors of the NEJM study conclude that not only will there be great public health benefits from reducing dietary salt, but that there will be substantial cost savings resulting from this decrease in salt intake and the resultant decrease in cardiovascular disease. Since their conclusions flow from a complex model it’s hard to know how much of these conclusions are valid. I suspect that the benefit they anticipate is less than they believe for two reasons. First there’s the large salt insensitive part of the population I’ve already mentioned. Second is that there are no data showing that cardiovascular events significantly decrease when an undifferentiated population decreases its salt intake. There may well such a benefit, but it’s speculative and likely much smaller than these authors think.
Regardless of the final resolution of this issues there’s another agenda at work in this article. It’s more political than scientific. Having decided that a reduction in salt intake is in the best interests of the public the authors conclude that government coercion is the only way to force a lower salt diet on an unwilling public. “Changes in behavior are notoriously difficult to achieve, and attempts to lower dietary salt intake on an individual basis have largely proved to be ineffective.” Here they stop being scientists and become social engineers. They want the federal government to intervene and regulate salt. They specifically mention the Food and Drug Administration. They obviously think they know better than those who disregard their learned advice and that these unwilling citizens should be forced to do what’s best for them regardless of their wishes to the contrary.
This is the all too typical presumption of people who have expertise in one special area and who think this entitles them to competence in other areas where their opinion or knowledge is no better than that of anyone else. What they’re saying is that educating the public about the dangers of high salt intake is only good if the public does as told. If they don’t they must be forced. Personal liberty is not an idle abstruse point; it’s a central pillar of a free society. That the NEJM saw nothing strange about this view, indeed they published a supporting editorial, tells us a lot about the Journal and about those who have our “best interests” at heart. The lack of faith in education shown by a periodical whose only function is education is staggering. Who will save us from our saviors?
William Buckley famously said that he’d rather be governed by the first 1000 names in the Boston telephone directory than the Harvard faculty. I wonder if these same 1000 Bostonians might make better public health decisions than the editorial board of the NEJM.