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The sodium, potassium, and iodine intake, and blood pressure of New Zealand school children: A cross-sectional survey

Published online by Cambridge University Press:  24 July 2025

H. Eyles
Affiliation:
Department of Epidemiology and Biostatistics, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, 1142, New Zealand
J. Rapson
Affiliation:
Department of Epidemiology and Biostatistics, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, 1142, New Zealand
K. Fuavao
Affiliation:
Department of Epidemiology and Biostatistics, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, 1142, New Zealand
Y. Jiang
Affiliation:
Department of Statistics, Faculty of Science, The University of Auckland, Auckland, 1142, New Zealand
G. Kira
Affiliation:
Te Hau Kori - Centre for Physical Activity and Wellbeing, Victoria University of Wellington, Wellington, 6140, New Zealand
C. Wall
Affiliation:
Department of Nutrition and Dietetics, Faculty of Medical and Health Sciences, The University of Auckland, Auckland, 1142, New Zealand
S. Skeaff
Affiliation:
Department of Human Nutrition, University of Otago, Dunedin, 9054, New Zealand
S. Grimes
Affiliation:
Institute of Physical Activity and Nutrition, School of Exercise and Nutrition Sciences, Deakin University, Melbourne, 3125, Australia
R. McLean
Affiliation:
Department of Preventive and Social Medicine, Dunedin School of Medicine, Dunedin, University of Otago, 9054, New Zealand
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Abstract

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In childhood, diets high in sodium and low in potassium contribute to raised blood pressure and cardiovascular disease later in life(1). For New Zealand (NZ) children, bread is a major source of dietary sodium, and fruit, vegetables, and milk are major dietary sources of potassium(2,3). However, it is mandatory to use iodised salt in NZ bread meaning reducing the salt and thus sodium content could put children at risk of iodine deficiency(4). Our objective was to measure the sodium, potassium, and iodine intake, and blood pressure of NZ school children 8-13 years old. A cross-sectional survey was conducted in five primary schools in Auckland and Dunedin. Primary schools were recruited between July 2022 and February 2023 using purposive sampling. Seventy-five children (n= 37 boys, 29 girls, and nine children who did not state their gender) took part. The most common ethnicity was NZ European and Other (n=54 or 72%) followed by Māori (indigenous inhabitants; n=9 or 12%) and Pasifika (n=5 or 7%). The main outcomes were 24-hour sodium and potassium intake, sodium to potassium molar ratio, 24-hour iodine intake, and BP. Sodium, potassium, and iodine intake were assessed using 24-hour urine samples and BP was assessed using standard methods. Differences by gender were tested using two-sample t-tests and nonparametric Wilcoxon two-sample tests. The mean (SD) 24-hour sodium excretion, potassium excretion, and sodium to potassium molar ratio for children with complete samples (n=59) were 2,420 (1,025) mg, 1,567 (733) mg, and 3.0 (1.6), respectively. The median (25th, 75th percentile) urinary iodine excretion was 88 (61, 122) µg per 24 hours and the mean (SD) systolic and diastolic blood pressure (n=74) were 105 (10) mmHg and 67 (9) mmHg, respectively. There was a significant difference between boys and girls for iodine (77 (43, 96) vs. 98 (72, 127) µg per 24 hours; p=0.02) but no other outcomes. In conclusion, children consumed more sodium and less potassium and iodine than World Health Organization recommendations(5). However, future research should confirm these findings in a nationally representative sample. Evidence-based, equitable interventions and policies with adequate monitoring should be considered to reduce potentially suboptimal sodium, potassium, and iodine intakes in New Zealand.

Information

Type
Abstract
Copyright
© The Author(s), 2025. Published by Cambridge University Press on behalf of The Nutrition Society

References

Leyvraz, M, Chatelan, A, Da Costa, BR, et al. (2018) Int J Epidemiol 1, 47(6), 1796–810Google Scholar
Eyles, H, Bhana, N, Lee, S, et al. (2018) Nutrients, 10(9), 1198Google Scholar
Parnell, W. (2003) NZ Food NZ Children Key results of the 2002 National Children’s Nutrition Survey Wellington: Ministry of Health, https://www.health.govt.nz/system/files/2011-11/nzfoodnzchildren.pdf Google Scholar
Skeaff, SA, Lonsdale-Cooper, E, (2013). Br J Nutr, 109(6), 1109–13CrossRefGoogle Scholar