Today's Boston Globe has a balanced article on the ongoing controversy about the health aspects of dietary salt. Unlike many journalists, however, Globe reporter Judy Foreman focuses on the right question: "Is lowering salt consumption important for health." After the obligatory quoting of an anti-salt advocate, in this case Dr. Lawrence Appel of Johns Hopkins who pointed out 1) lowering salt can reduce blood pressure and, 2) loweirng dietary salt is "easier for morst people than ... making other dietary changes", Foreman states that "lowering blood pressure by salt reduction may not translate to a survival advantage, quoting Dr. Hillel Cohen of New York City's Albert Einstein College of Medicine who explained the most recent study: "people who reduced salt actually had a 37 percent greater risk of death than those who didn't." Foreman makes it clear that "The Salt Institute did not pay for the study." Actually, Foreman neglects to mention, the data Dr. Cohen analyzed is from the federal government's own NHANES II database.
Congratulations to the Globe and Ms. Foreman for recognizing that the proper question is the health outcome of any intervention (e.g. survivability or, in this case, it might be incidence of heart attacks) not impact on an intermediate variable like blood pressure. There are many metabolic changes that occur when a person reduces dietary salt. Blood pressure is one. Dangerously increasing insulin resistance is another. Yet another is stimulation of the renin-agiotensen system; high plasma renin activity has been shown to produce dramatically higher rates of heart attacks. Next time someone tells you that reducing salt can lower your blood pressure (it can, though in a minority of the population), remind them that none of the 13 reported studies of whether reducing dietary salt actually improves health outcomes, none, has suggested a lower salt diet is healthier. None.
