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BMJ Open. 2017 Oct 30;7(10):e016639. doi: 10.1136/bmjopen-2017-016639.

Dietary intake and sources of sodium and potassium among Australian schoolchildren: results from the cross-sectional Salt and Other Nutrients in Children (SONIC) study.

Author information

Institute for Physical Activity and Nutrition, Deakin University, Geelong, Australia.
Wolfson Institute of Preventative Medicine, Barts and The London School of Medicine and Dentistry, Queen Mary University of London, London, UK.



To 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.


Cross-sectional study.


Primary schools located in Victoria, Australia.


666 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.


24-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.


Participants 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.


For 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.


Australia; child; potassium; sodium chloride, dietary; sodium, dietary

[Indexed for MEDLINE]
Free PMC Article

Conflict of interest statement

Competing interests: All authors have completed the Unified Competing Interest form at (available on request from the corresponding author) and declare: CAG received financial support in the form of a postgraduate scholarship and postdoctoral fellowship from the Heart Foundation, Australia, for the submitted work; JRB received financial support in the form of a postgraduate scholarship from the Heart Foundation, Australia. CAN has received research funds from Meat & Livestock Australia; National Health and Medical Research Council, Wicking Foundation, National Heart Foundation, Australia, Helen MacPherson Smith Trust and Red Cross Blood Bank. These payments are unrelated to the submitted work. LJR has received research funds from Meat & Livestock Australia. These payments are unrelated to the submitted work. CAG and CAN are members of World Action on Salt and Health (WASH) and Australian Division of World Action on Salt and Health (AWASH). FJH is a member of Consensus Action on Salt & Health (CASH) and WASH. CASH, WASH and AWASH are non-profit charitable organisations and no authors receive any financial support. KJC and KB had no support from any organisation for the submitted work and no other relationships or activities that could appear to have influenced the submitted work.

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