ObjectivesTo examine sodium and potassium urinary excretion by socioeconomic status (SES), discretionary salt use habits and dietary sources of sodium and potassium in a sample of Australian schoolchildren.DesignCross-sectional study.SettingPrimary schools located in Victoria, Australia.Participants666 of 780 children aged 4–12 years who participated in the Salt and Other Nutrients in Children study returned a complete 24-hour urine collection.Primary and secondary outcome measures24-hour urine collection for the measurement of sodium and potassium excretion and 24-hour dietary recall for the assessment of food sources. Parent and child reported use of discretionary salt. SES defined by parental highest level of education.ResultsParticipants were 9.3 years (95% CI 9.0 to 9.6) of age and 55% were boys. Mean urinary sodium and potassium excretion was 103 (95% CI 99 to 108) mmol/day (salt equivalent 6.1 g/day) and 47 (95% CI 45 to 49) mmol/day, respectively. Mean molar Na:K ratio was 2.4 (95% CI 2.3 to 2.5). 72% of children exceeded the age-specific upper level for sodium intake. After adjustment for age, sex and day of urine collection, children from a low socioeconomic background excreted 10.0 (95% CI 17.8 to 2.1) mmol/day more sodium than those of high socioeconomic background (p=0.04). The major sources of sodium were bread (14.8%), mixed cereal-based dishes (9.9%) and processed meat (8.5%). The major sources of potassium were dairy milk (11.5%), potatoes (7.1%) and fruit/vegetable juice (5.4%). Core foods provided 55.3% of dietary sodium and 75.5% of potassium while discretionary foods provided 44.7% and 24.5%, respectively.ConclusionsFor most children, sodium intake exceeds dietary recommendations and there is some indication that children of lower socioeconomic background have the highest intakes. Children are consuming about two times more sodium than potassium. To improve sodium and potassium intakes in schoolchildren, product reformulation of lower salt core foods combined with strategies that seek to reduce the consumption of discretionary foods are required.

BackgroundDietary sodium and potassium are involved in the pathogenesis of cardiovascular disease. Data exploring the cardiovascular outcomes associated with these electrolytes within Australian children is sparse. Furthermore, an objective measure of sodium and potassium intake within this group is lacking.ObjectiveThe primary aim of the Salt and Other Nutrient Intakes in Children (“SONIC”) study was to measure sodium and potassium intakes in a sample of primary schoolchildren located in Victoria, Australia, using 24-hour urine collections. Secondary aims were to identify the dietary sources of sodium and potassium, examine the association between these electrolytes and cardiovascular risk factors, and assess children’s taste preferences and saltiness perception of manufactured foods.MethodsA cross-sectional study was conducted in a convenience sample of schoolchildren attending primary schools in Victoria, Australia. Participants completed one 24-hour urine collection, which was analyzed for sodium, potassium, and creatinine. Completeness of collections was assessed using collection time, total volume, and urinary creatinine. One 24-hour dietary recall was completed to assess dietary intake. Other data collected included blood pressure, body weight, height, waist and hip circumference. Children were also presented with high and low sodium variants of food products and asked to discriminate salt level and choose their preferred variant. Parents provided demographic information and information on use of discretionary salt. Descriptive statistics will be used to describe sodium and potassium intakes. Linear and logistic regression models with clustered robust standard errors will be used to assess the association between electrolyte intake and health outcomes (blood pressure and body mass index/BMI z-score and waist circumference) and to assess differences in taste preference and discrimination between high and low sodium foods, and correlations between preference, sodium intake, and covariates.ResultsA total of 780 children across 43 schools participated. The results from this study are expected at the end of 2015.ConclusionsThis study will provide the first objective measure of sodium and potassium intake in Australian schoolchildren and improve our understanding of the relationship of these electrolytes to cardiovascular risk factors. Furthermore, this study will provide insight into child taste preferences and explore related factors. Given the cardiovascular implications of consuming too much sodium and too little potassium, monitoring of these nutrients during childhood is an important public health initiative.

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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.