The Iodine Status of Queensland Preschool Children After the Introduction of Mandatory Iodine Fortification in Bread: An Exploratory Study Using a Convenience Sample

Abstract

Introduction Appropriate dietary iodine is essential for thyroid hormone synthesis, especially in young children. Following an iodine fortification in bread initiative, approximately 6 % of Australian preschool children were expected to have an excessive iodine status. The aim of this study was to document the current iodine status of preschool children using urinary iodine concentration (UIC) as a biomarker of iodine intake. Methods A convenience sample of fifty-one preschool children, aged 2-3 years, were recruited from south east Queensland. UIC was ascertained from spot morning and afternoon urine samples collected on two consecutive days and food frequency questionnaires were completed for each participant. Dietary iodine intake was extrapolated from UIC assuming 90 % of dietary iodine is excreted in urine and a urine volume of 0.5 L/day. Results A median UIC of 223.3 μg/L was found. The calculated median dietary iodine intake was 124.8 μg/day (SD 47.0) with 9.8 % of samples above the upper level of 200 μg for dietary iodine for children within this age group. No foods were associated with UIC. Discussion Limited by sample size and recruitment strategies, no association was found between usual food intake and UIC. Extrapolated dietary iodine intake indicated that children within this cohort consumed adequate amounts of dietary iodine, although the number of children consuming above the upper limit of 300 μg/day was almost double of expected. The development of a UIC criteria to assess appropriate parameters for varying degrees of iodine status is required for the monitoring of iodine nutrition in this vulnerable age group.

Iodine Intakes of Victorian Schoolchildren Measured Using 24-h Urinary Iodine Excretion

“…There was, however, no difference in UIE between the different socioeconomic groups. These findings, along with those of other studies conducted post-fortification of bread with iodized salt [ 25 , 58 ], provide evidence that compared to pre-fortification data Australian schoolchildren are now iodine replete. Therefore, it appears that the iodine intakes of Australian schoolchildren have increased to sufficiency since the introduction of mandatory fortification of bread with iodized salt.…”

“…In order to combat the re-emergence of deficiency, mandatory fortification of all commercially-produced yeast-leavened bread, excluding organic bread, with iodized salt was implemented in 2009 [ 21 ]. Studies conducted post-fortification utilizing spot urine samples, including the 2011–2013 Australian Health Survey (AHS), have reported an improvement in iodine status among children and adults, when compared to pre-fortification [ 22 , 23 , 24 , 25 , 26 ].…”

Food sources of iodine in schoolchildren and relationship with 24-h urinary iodine excretion in Victoria, Australia

“…Following the success of voluntary fortification of bread with iodised salt in Tasmania (19) , mandatory fortification of all commercially produced bread in Australia (excluding organic varieties) with iodised salt was implemented in 2009 (20) . Studies conducted post-fortification with the use of iodised salt in bread have observed an improvement in iodine status (21)(22)(23)(24)(25)(26)(27) .…”