Iodine status and Growth in 0-2 year old children on cow's milk protein free diets

Introduction: Allergy to cow s milk protein is the most common food allergy in children under the age of three years. A diet without milk or dairy products is potentially low in many nutrients and could put the child at risk of malnutrition and compromised growth. Dairy products are a major source of iodine in the Norwegian diet, and excluding dairy products may negatively affect iodine status. Insufficient iodine status during childhood could potentially be detrimental and put the child at risk for delays in mental development and poor growth. Objectives: The main objectives of this study was to investigate iodine intake and status along with growth in infants and young children under two years of age who were on a cow s milk protein free diet and to identify factors affecting iodine status and growth in these children. Methods: Fifty-seven infants and children under two years of age where included in a larger cross-sectional study on the nutritional status of children on cow s milk protein free diets (MILKID study). Two spot urine samples from were collected and analysed for iodine, together with a three day food record and a food frequency questionnaire on dietary sources of iodine. Urine iodine concentrations were compared to the WHO cut-off values for iodine deficiency. Weight, length and head circumference were recorded at birth and at inclusion in the study and compared to the Norwegian growth standard. Sub-group analyses were done on different feeding patterns, according to weaning status. Results: One third of the children had iodine deficiency according to urine iodine concentration (UIC). Children who were mainly breastfed were at highest risk and 58 % was classified as deficient. Dietary factors associated with iodine were intake of enriched baby cereals (r = 0.230, p = 0.02) and reaching RDI for iodine through diet (r=0.313, p = 0.03). Children of mothers who took supplement with iodine had higher urinary iodine concentrations, though this was not significant. Growth in length was compromised in boys, 11 % of the infants had weight for age z-score (WAZ) and BMI for age z-score (BMIZ) of ≤ -2 and 5 % length for age z-scores (LAZ) of ≤ -2 at inclusion and this was associated with food refusal and low appetite, but not associated with iodine deficiency. Conclusion: The present study demonstrates that the exclusion of cow s milk protein puts the child at risk of deficiency of iodine and poor growth, however the two conditions were not related. Infants reliant on breast milk as their main iodine source are at increased risk of iodine deficiency. Boys with feeding problems were at highest risk of growth failure