Abstract P048: Sodium Intake is Associated with Weight Status in Australian Schoolchildren Aged 4-12 Years

Introduction: A high sodium intake stimulates thirst and in turn may promote greater consumption of high energy sugary beverages, which are linked to obesity risk in children. In this study we assessed the hypothesis that sodium intake, as measured by 24-hr urinary sodium excretion, would be positively associated with weight status in primary school-aged children. Methods: Cross-sectional study completed within a convenience sample of Victorian primary schools (n=43). Sodium intake was assessed via one 24-hr urine collection. Fourteen percent of samples were deemed invalid and excluded. BMI was calculated from measured weight and height and converted to BMI z-scores using the 2000 Centers for Disease Control and Prevention reference growth charts. Participants were grouped into weight categories using the International Obesity Task Force cut-points. Differences in sodium intake and weight status were assessed using multi-level linear and logistic regression analysis with adjustment for random effects (gender, age) and fixed effect (school cluster). Results: Of the 667 children with valid urine samples 55% were male and the average age was 9.3±(SD) 1.8 years. Ten percent were classified as underweight, 73% healthy weight, 14% overweight and 3% obese. Average sodium intake differed across weight categories, underweight 82±29 mmol/day (salt equivalent 4.8±1.7 g/day); healthy weight 102±43 mmol/day (salt 6.0±2.5 g/day); overweight 125±55 mmol/day (salt 7.3±3.2 g/day); obese 148±97 mmol/day (salt 8.7±5.7 g/day) (p=0.001). In the fully adjusted model sodium intake (mmol/d) was significantly associated with BMI z-score (b=0.006, P<0.001). A 17 mmol/day increase in sodium intake (salt 1 g/day) was associated with a 23% (OR: 1.23; 95% CI 1.16, 1.31) greater risk of being overweight or obese, adjusted for age and gender. Conclusions: Higher sodium intake is associated with overweight and obesity in Victorian schoolchildren. This may be related to increased energy intake, and this association should be explored further.