To Be Taken With a Grain of Salt

I want to raise a question about the sources supporting the belief that excessive sodium chloride intake is related to high blood pressure and therefore heart disease because your summary of heart-protecting measures suggests that reducing salt intake would be beneficial for heart health despite numerous studies that have called that belief into question.

In 2011, Scientific American published an article by Melinda Wenner Moyer, “It’s Time to End the War on Salt,” that led off with this statement:

“…a meta-analysis of seven studies involving a total of 6,250 subjects in the American Journal of Hypertension found no strong evidence that cutting salt intake reduces the risk for heart attacks, strokes or death in people with normal or high blood pressure. In May, European researchers publishing in the Journal of the American Medical Association reported that the less sodium that study subjects excreted in their urine—an excellent measure of prior consumption—the greater their risk was of dying from heart disease. These findings call into question the common wisdom that excess salt is bad for you, but the evidence linking salt to heart disease has always been tenuous.”

On the other hand, a 2021 report published by BloodPressure UK refutes these findings, claiming that inappropriate research methods, conflicts of interest, lack of public access to data supporting the research, and scientific and professional conduct in publishing research which at times have not been properly reviewed,  journal responsibility in publishing low-quality controversial research and inadequate review processes, grants, research and ethics committee approvals for inappropriate study designs and methods, health and scientific organization issues, and lack of government oversight. 

At the same time, however, this critical article does NOT cite any more convincing research to support the sodium argument. 
Sussing out the answers to this question may in fact be impossible because there are so many other factors affecting heart health. Only controlled experiment in which an experimental group is fed measured amounts of sodium over an extended period under controlled conditions that also measure the other heart-affecting environmental factors would ever be able to “prove” this belief one way or the other. 

Such a research project could take decades to deliver a meaningful result such as the ones from the Framingham Heart Study which, by the way, never attempted to study the impact of sodium chloride on high blood pressure and therefore heart disease. It’s probably too late now to retroactively study the data from the FHS to make a clear-cut determination about the real risks of salt intake…but that would have been very interesting.

This proves the point that ALL scientific research – and, in fact, all pubic statements of fact – need to be taken along with a suitably large helping of salt.