Conventional Wisdom on Salt Questioned
A JAMA study calls into question the current dogma on limiting the population’s salt intake and on salt’s health effects. Initial reaction to the study, as reported in the New York Times, is skeptical.
Researchers followed a European cohort comprising roughly 3700 subjects without cardiovascular disease at baseline. All had 24-hour urine sodium excretion measured at enrollment.
After a median follow-up of almost 8 years, cardiovascular mortality was highest among participants in the lowest tertile of sodium excretion, and the inverse-association trend retained statistical significance after multivariable adjustment. Sodium excretion was not associated with all-cause mortality.
The incidence of hypertension did not rise with increasing tertiles of sodium excretion. Each 100-mmol increase in excretion was associated with a 1.7-mm Hg increase in systolic pressure, but diastolic pressure did not correlate with excretion.
The authors note that their findings “do not negate the blood pressure-lowering effects of a dietary salt reduction in hypertensive patients.” Critics echo the authors’ own list of their study’s limitations, including the relative youthfulness of the cohort (averaging about age 40), and the inclusion of only white Europeans.