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High, low sodium intake linked to increased mortality
Both low and high sodium intakes are correlated with increased mortality, according to results from a recent meta-analysis.
Researchers searched the PubMed database to identify population samples from prospective cohort studies and randomized controlled trials. Eligible studies included those providing individual measures of dietary sodium intake, as well as randomized clinical trials that assigned participants to low- (<2,645 mg), usual- (2,645 mg-4,945 mg) or high-sodium diets (>4,945 mg), with outcome data on all-cause mortality and/or CV mortality/morbidity.
The search did not yield any eligible randomized controlled trials with healthy population samples; analysis included data from 23 cohort studies and two follow-up studies to randomized trials (n=274,683).
Among participants with usual vs. lower sodium intake, the risks for all-cause mortality and CVD events were reduced (HR=0.91; 95% CI, 0.82-0.99 for mortality; HR=0.9; 95% CI, 0.82-0.99 for CVD), whereas risk increased with high vs. usual sodium intake (HR=1.16; 95% CI, 1.03-1.3 for mortality; HR=1.12; 95% CI, 1.02-1.24 for CVD).
After adjustment for confounders, the HR for all-cause mortality was uniformly reduced for usual vs. low sodium intake (HR=0.86; 95% CI, 0.81-0.92) but was not elevated for high vs. usual sodium intake (HR=1.04; 95% CI, 0.91-1.18) in analysis of population-representative samples. Sub-analyses assessing the effect of sodium intake on CV-related mortality and risk for stroke yielded similar results. Sensitivity analysis including only studies that determined sodium intake via urine analysis also did not alter results.
According to the researchers, these findings suggest an optimal range for daily sodium intake of 2,645 mg to 4,945 mg.
“Our study extends [an] Institute of Medicine report by identifying a specific range of sodium intake associated with the most favorable health outcomes, within which variation in sodium intake is not associated with variation in mortality,” the researchers wrote. “Moreover, this optimal range of intake, based upon available evidence, is coterminous with the current dietary intake of most of the world’s population, and is in accordance with the IOM rules for definition of an adequate intake level and upper limit of sodium. … These data are consistent with the hypothesis that a U shape best describes the relationship of sodium intake to health outcomes.”
Disclosure: The researchers report no relevant financial disclosures.