Sufficient iodine status among Norwegian toddlers 18 months of age - cross-sectional data from the Little in Norway study

Background: Inadequate iodine intake has been identified in several population groups in the Nordic countries over the past years; however, studies of iodine status in infants and toddlers are scarce. Objective: The aim of this study is to evaluate the iodine status and dietary iodine sources among 18-month-old toddlers from Norway. Methods: Cross-sectional and country representative data from the Little in Norway study were used. All children who had given a spot urine sample at 18 months age were included (n = 416). Urinary iodine concentration (UIC) was determined by inductively coupled plasma mass-spectrometry. Dietary habits and supplement use were measured by a food frequency questionnaire. Results: Median (25th-75th percentiles [p25-p75]) UIC was 129 (81-190) mu g/L while estimated median (p25-p75) habitual iodine intake was 109 (101-117) mu g/day. None of the children were below the estimated average requirement (EAR) of 65 mu g/day or above the upper intake level of 180 mu g/day. There were no differences in either UIC or estimated habitual iodine intake between different geographic areas in Norway. Milk was the most important iodine source, contributing an estimated 70% to the total iodine intake, while other foods rich in iodine such as seafood and enriched baby porridge contributed about 30%. Conclusions: The iodine status among 18-month-old toddlers from different geographic areas in Norway was sufficient, indicated by a median UIC above the WHO cutoff of 100 mu g/L. This was further supported by the estimated habitual iodine intake, where none of the participants were below the EAR. Milk was an important iodine source in this age group; thus children with a low intake might be at risk of insufficient iodine intake.