Iodine intake and its association with sociodemographic and dietary factors in Australian preschool children.

purposeImbalanced iodine intakes in early childhood may impair growth and neurodevelopment, yet iodine intake in Australian preschoolers remains poorly characterised. This study aimed to assess the prevalence of inadequate and excessive iodine intake, identify sociodemographic and dietary factors associated with iodine intakes, and determine dietary sources of iodine in Australian children aged 2-5 years.

methodsData of children aged 2-5 years (n = 762) from the 2011-2013 National Nutrition and Physical Activity Survey were analysed. Dietary intake was assessed using up to two 24-h recalls, with usual intakes estimated via the Multiple Source Method. The proportion of children meeting the Estimated Average Requirement for iodine (EAR; 65 µg/day for 1-8-year-olds) or exceeding the Upper Level of Intake for iodine (UL; 200 µg/day for 1-3-year-olds and 300 µg/day for 4-8-year-olds) was calculated for the whole sample (2-5-year-olds) and for each age group (2-, 3-, 4-, and 5-year olds). Children were classified by dietary pattern (omnivores, vegetarian/vegan) and dairy consumption. Multivariable linear regression assessed associations between iodine intake and sociodemographic and dietary factors. Analyses accounted for complex survey design.

resultsMean iodine intake was 148.9 µg/day (95% CI: 145.0, 152.8 µg/day; median: 143.5 µg/day; 25th, 75th percentiles: 120.2, 175.1 µg/day). Few 2-5-year-old children (1.1%) had iodine intakes below the EAR, while intakes in 18.4% of 2-year-old children and 14.9% of 3-year-old children exceeded the UL; none (0%) of 4-5‑year‑old children had iodine intakes that exceeded the UL. Intake declined with age (-7.5 µg/day; 95% CI: -10.5, -4.5 µg/day) and was higher in children from food-secure than food-insecure households (mean difference: 16.0 µg/day; 95% CI: 7.3, 24.8 µg/day). Dairy avoiders had lower intakes than consumers (mean difference: 25.7 µg/day; 95% CI: 11.1, 40.3 µg/day). No differences were observed by dietary pattern. Major iodine sources were dairy milk (34.8%), bread/bread rolls (24.4%), cereal-based dishes (4.8%), and yoghurt (4.5%).

conclusionsWhile inadequate intake was uncommon, excessive iodine intake affected over 1 in 7 2- and 3-year-old children. Iodine intake declined with age and was lower in children from food-insecure households and those avoiding dairy. Strategies are needed to address excess and inadequacy in vulnerable groups.