Association between 24-hour urinary sodium excretion and obesity in Korean adults: a multi-center study

Abstract Objective The present study aimed to explore the association between sodium intake, as assessed by 24-hour urinary sodium excretion, and various obesity parameters among South Korean adults. The associations of 24-hour urinary sodium excretion and sodium intake calculated from the dietary questionnaire with obesity parameters were also compared. Methods This multi-centered, cross-sectional study analyzed data of 640 healthy adults from 8 provinces in South Korea. Obesity was assessed through body mass index (BMI), waist circumference (WC), waist-to-hip ratio (WHR), and waist-to-height ratio (WHtR). Mean 24-hour urinary sodium excretion was calculated from repeatedly collected 24-hour urine samples. Participants’ dietary intake was assessed through 24-hour dietary recall interview on the days prior to 24-hour urine collection. Results In both sexes, the means of all anthropometric measurements tended to increase proportionally with 24-hour urinary sodium excretion quartiles, irrespective of adjustment. Men in the highest quartile (Q4) of 24-hour urinary sodium excretion had increased odds of obesity (as assessed by BMI, WC, WHR, and WHtR) compared to men in the 3 lower quartiles (Q1–Q3) of 24-hour urinary sodium excretion. Women in Q4 of 24-hour urinary sodium excretion exhibited a higher chance of general obesity and abdominal obesity. Sodium intake calculated from the dietary questionnaire was not significantly associated with obesity in both sexes. Conclusions In Korean adults, there was a positive association between higher sodium intake as assessed by 24-hour urinary sodium excretion and obesity independent of energy intake.