Decreased Hydration, Elevated Serum Sodium Possibly Linked to Accelerating Aging

Individuals whose fasting sodium serum levels exceed 142 mmol/L are at an increased risk to be biologically older, to develop chronic diseases, and to die at a younger age, according to the results of a cohort analysis of data from the ongoing, population-based, prospective Atherosclerosis Risk in Communities (ARIC) study. These findings were published in the journal EBioMedicine.

Researchers sought to test the theory that optimal hydration may slow down the aging process in humans. The main goal of their analysis was to learn whether higher serum sodium levels at middle age are linked to accelerated aging and to identify serum sodium thresholds that can be utilized in clinical practice to identify those individuals at risk who might possibly benefit from improved hydration.

The 2 main age-related outcomes measured were age-related chronic diseases and all-cause mortality. These indicators of aging were used as outcome variables in the time-to-event analyses, with middle age serum sodium as the exposure variable. The third measure of the aging process that was utilized in the study was biological age, which was calculated from age-dependent biomarkers.

Data from 15,752 individuals aged 45 to 66 years a total of 25 years of follow-up were included. Serum sodium levels were used as a proxy for hydration habits. Biological age was calculated from age-dependent biomarkers to estimate the relative speed of aging. Risk for chronic diseases and mortality were evaluated as well.

Results of the study showed that middle-age serum sodium levels of higher than 142 mmol/L were associated with a 39% increased risk for the development of chronic diseases (hazard ratio [HR], 1.39; 95% CI, 1.18-1.63), and serum sodium levels of higher than 144 mmol/L were associated with a 21% increased risk for premature mortality (HR, 1.21; 95% CI, 1.02-1.45).

Individuals with serum sodium levels higher than 142 mmol/L had up to a 50% higher likelihood of being older than their chronological age (odds ratio, 1.50; 95% CI, 1.14-1.96). Additionally, a higher biological age was associated with an increased risk for chronic diseases (HR, 1.70; 95% CI, 1.50-1.93) and for premature mortality (HR, 1.59; 95% CI, 1.39-1.83).

A key limitation of the study is its observational design, which is associated with the possibility of residual confounding. Additionally, endogeneity might be present in the analyses of associations between serum sodium levels and biological age, because of the potential effects of hydration on some of the biological age biomarkers, including creatinine, albumin, and urea nitrogen.

“Worldwide surveys find that more than 50% of people do not drink the recommended amounts of fluids,” the study authors wrote. “Therefore, results of our study provide additional reasons for reinforcing already existent recommendations for optimal fluid intake.”