Association between sodium intake, spot urine sodium concentration and obesity in Finnish adults: A population-based study

Abstract

Background: Growing evidence suggests positive association between sodium intake and the risk of obesity. Evidence on this topic is lacking from Finland, despite the population's historically high sodium intake and long-standing national salt reduction initiatives. Aims: To examine whether sodium intake and spot urine sodium concentration are associated with general or abdominal obesity in Finnish adults. Methods: We used cross-sectional, population-based data of the National FinHealth 2017 Study (men=2222, women=2792, ≥18 years-old). Sodium intake was estimated using a validated food frequency questionnaire. A subsample of participants provided spot urine samples (men=558; women=702). General and abdominal obesity were assessed using body mass index and waist circumference. Associations on sex-specific quartiles were examined using multinomial logistic regression, adjusting for key sociodemographic and lifestyle confounders. Spot urine samples were validated against 24-h urine collections. Results: Women in the highest quartile of sodium intake had higher odds of general obesity (OR 4.30, 95% CI 2.60–7.12) and abdominal obesity (OR 3.42, 95% CI 2.11–5.56) compared with the lowest quartile. Men in the highest quartile of urine sodium concentration had higher odds of general obesity (OR 6.05, 95% CI 2.83–12.93) and abdominal obesity (OR 4.68, 95% CI 2.44–8.96) compared with the lowest quartile. Spot urine samples showed moderate agreement with 24-h urine collections, with a Spearman's rho of 0.45. Conclusion: In this cross-sectional analysis, higher dietary sodium intake and urine sodium concentration were associated with higher odds of general and abdominal obesity. Prospective studies are needed to confirm causality and to better understand underlying biological mechanisms.