Dietary salt intake assessed by 24 h urinary sodium excretion in Australian schoolchildren aged 5-13 years

Abstract

Objective: To measure total daily salt intake using 24 h urinary Na excretion within a sample of Victorian schoolchildren aged 5-13 years and to assess discretionary salt use habits of children and parents.

Design: Cross-sectional study.

Setting: Completed within a convenience sample of independent primary schools (n 9) located in Victoria, Australia.

Subjects: Two hundred and sixty children completed a 24 h urine collection over a school (34%) or non-school day (66%). Samples deemed incomplete (n 18), an over-collection (n 1) or that were incorrectly processed at the laboratory (n 3) were excluded.

Results: The sample comprised 120 boys and 118 girls with a mean age of 9.8 (SD 1.7) years. The average 24 h urinary Na excretion (n 238) was 103 (SD 43) mmol/24 h (salt equivalent 6.0 (SD 2.5) g/d). Daily Na excretion did not differ by sex; boys 105 (SD 46) mmol/24 h (salt equivalent 6.1 (SD 2.7) g/d) and girls 100 (SD 41) mmol/24 h (salt equivalent 5.9 (SD 2.4) g/d; P=0.38). Sixty-nine per cent of children (n 164) exceeded the recommended daily Upper Limit for Na. Reported discretionary salt use was common: two-thirds of parents reported adding salt during cooking and almost half of children reported adding salt at the table.

Conclusions: The majority of children had salt intakes exceeding the recommended daily Upper Limit. Strategies to lower salt intake in children are urgently required, and should include product reformulation of lower-sodium food products combined with interventions targeting discretionary salt use within the home.

Fig. 1

Daily sodium intake (mmol/d) compared with dietary recommendations (Upper Limit: 4–8 years = 60 mmol/d; 9–13 years = 86 mmol/d^{( 15 )}) by age group: (a) 5–8 years (n 83); (b) 9–13 years (n 155). Primary-school children attending nine independently funded schools, Victoria, Australia, June 2010–June 2011

Fig. 2

Discretionary salt use habits of study participants and their parents ( , ‘yes, usually’; , ‘yes, sometimes’; , ‘no’). Primary-school children (n 238) attending nine independently funded schools, Victoria, Australia, June 2010–June 2011