Scientific Opinion on Dietary Reference Values for iodine

Abstract

Following a request from the European Commission, the Panel on Dietetic Products, Nutrition and Allergies (NDA) derived Dietary Reference Values (DRVs) for iodine, which are provided as Adequate Intake (AI). Iodine is essential for the synthesis of thyroid hormones. Through these hormones, iodine has an important role in energy-yielding metabolism and many other physiological processes. Iodine deficiency is associated with an increased frequency of goitre and hypothyroidism in a population. The AI for iodine is based on a large epidemiological study in European school-aged children showing that goitre prevalence is lowest for a urinary iodine concentration above around 100 µg/L. From this study, a urinary iodine concentration of ≥ 100 µg/L has been accepted as the threshold indicating sufficient iodine intake of school-aged children. In the absence of similar suitable data for other age groups it is proposed that this threshold also be applied for adults, infants and young children. Taking into account urinary volume and an absorption efficiency for iodine of 92 %, an AI of 150 µg/day is proposed for adults. For infants aged 7-11 months and for children, AIs range between 70 µg/day and 130 µg/day. For pregnant women, an AI of 200 µg/day is proposed, taking into account additional needs due to increased maternal thyroid hormone production and the iodine uptake by the fetus, placenta and amniotic fluid. The proposed AI for lactating women of 200 µg/day takes into account the existence of large iodine stores in conditions of adequate iodine status before pregnancy and considers that a full compensation for the iodine secreted in breast milk is not justified for the derivation of an AI for iodine for lactating women.