Salt shakes its bad rap for upping risk of death, heart diseases

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Take it with a grain of salt: In older adults, self-reported sodium intake was not associated with risk for cardiovascular disease, heart failure and mortality, according to a study published online Jan. 19 in JAMA Internal Medicine.

Starting in 1997, the research team enrolled 2,642 independent, older adults. Sodium intake was assessed at baseline using a food frequency questionnaire. Three sodium intake profiles emerged: less than 1,500, between 1,500 and 2,300 and more than 2,300 mg per day. Andreas P. Kalogeropoulos, MD, MPH, PhD, at the Emory Clinical Cardiovascular Research Institute at Emory University in Atlanta, and colleagues then followed patients for 10 years.

They found that while crude rates for developing cardiovascular disease, heart failure and mortality seemed higher at the outset, adjusting for sex and race mitigated most of the apparent difference between sodium intake groups. The lowest, middle and highest sodium groups had respective mortality rates of 33.8 percent, 30.7 percent and 35.2 percent. However, the hazard ratio per gram of sodium intake was 1.09 in the crude analysis and 1.03 when adjusted. Those at highest risk for mortality among patients were female, black, and/or without hypertension.

Over the course of 10 years, 28.9 percent of patients without initial cardiovascular disease developed it. Subhazard ratios per gram of sodium intake were the same as those for mortality risk. Incident rates for cardiovascular disease were 28.5 percent, 28.2 percent and 29.7 percent, respectively, for least, middle and most sodium consumption, when adjusted for competing mortality.

Heart failure developed in 15.1 percent of the patients in the study. The risk for heart failure was 1.03 per gram of sodium in the crude analysis, 1 per gram of sodium when adjusted. Least, middle, and most sodium intake experienced rates of heart failure of 15.7 percent, 14.3 percent and 15.5 percent, respectively.

“Compared with baseline sodium intake of 1500 to 2300 mg/d, no signal of benefit was observed with less than 1500mg/d of sodium intake,” wrote Kalogeropoulos et al. “However, a signal for potential harm was observed with greater than 2300mg/d of sodium intake, driven mainly by women and black participants, but this finding needs further confirmation because of nonsignificance and multiple subgroup testing.”

Other studies in the area have been equally confounding, some reporting no association, some positive and others an inverse relationship between mortality and sodium intake.

“Our data emphasize the need for stronger evidence, preferably from rigorous controlled trials testing additional thresholds for sodium intake, before applying a policy of further sodium restriction to older adults beyond the current recommendation for the general adult population (2300mg/d),” Kalogeropoulos et al wrote.