Heart Risks Higher at Highest and Lowest Salt Intake Level

Sodium intake that is too high or too low appears to be associated with an elevated risk of cardiovascular (CV) events in susceptible patients, according to a new study.

Researchers at McMaster University (Hamilton, Canada), Friedrich Alexander University (Erlangen-Nuremberg, Germany), and other institutions performed observational analyses of two study cohorts involving 28,880 subjects to determine the association between sodium intake and CV events in patients with established CV disease or diabetes mellitus. Sodium intake was estimated by 24-hour urinary sodium and potassium excretion from a morning fasting urine sample. The researchers then plotted the associations using proportional hazard models to determine CV death, myocardial infarction (MI), stroke, and hospitalization for congestive heart failure (CHF) as related to sodium intake.

The results showed that the relationship between sodium intake and the composite of cardiovascular death, MI, stroke, and CHF hospitalization was J-shaped, with elevated risks associated with consumption of more than 8,000 mg and less than 3,000 mg per day. Potassium intake, a proposed modifier of the relationship between sodium intake and CV disease, was associated with stroke risk only; compared with an intake of less than 1,500 mg/day, higher consumption was associated with reduced risks of stroke. The study was published in the November 23, 2011, issue of the Journal of the American Medical Association (JAMA).

“A more cautious approach to policy on sodium intake may be appropriate, one that targets sodium reduction in populations consuming high sodium levels and reflects the uncertainty in those with moderate sodium diets, which includes the majority of the population,” concluded lead author Martin O'Donnell, MB, PhD, and colleagues.

“A more natural diet would concurrently lead to an absolute increase in dietary potassium content and also lead to an improved sodium-potassium ratio, which may be more desirable than change of either electrolyte on its own,” commented Paul Whelton, MB, MD, of the Tulane University School of Public Health and Tropical Medicine (New Orleans, LA, USA), in an accompanying editorial. “The scientific underpinning for the health benefits from sodium reduction is strong, and the available evidence does not support deviating from the stated goal of reducing the exposure to dietary sodium in the general population.”

Related Links:
McMaster University
Friedrich Alexander University
Tulane University School of Public Health and Tropical Medicine