Multiple micronutrients in pregnancy and lactation: an overview

Following a request from the European Commission, the EFSA Panel on Dietetic Products, Nutrition and Allergies (NDA) was asked to deliver a Scientific Opinion on the nutrient requirements and dietary intakes of infants and young children in the European Union. This Opinion describes the dietary requirements of infants and young children, compares dietary intakes and requirements in infants and young children in Europe and, based on these findings, concludes on the potential role of young-child formulae in the diets of infants and young children, including whether they have any nutritional benefits when compared with other foods that may be included in the normal diet of infants and young children. The Panel concluded on the levels of nutrient and energy intakes that are considered adequate for the majority of infants and young children, and evaluated the risk of inadequate nutrient intakes in infants and young children in living Europe. Dietary intakes of alpha-linolenic acid (ALA), docosahexaenoic acid (DHA), iron, vitamin D and iodine (in some European countries) are low in infants and young children living in Europe, and particular attention should be paid to ensuring an appropriate supply of ALA, DHA, iron, vitamin D and iodine in infants and young children with inadequate or at risk of inadequate status of these nutrients. No unique role of young-child formulae with respect to the provision of critical nutrients in the diet of infants and young children living in Europe can be identified, so that they cannot be considered as a necessity to satisfy the nutritional requirements of young children when compared with other foods that may be included in the normal diet of young children (such as breast milk, infant formulae, follow-on formulae and cow‘s milk). © European Food Safety Authority, 2013

Scientific Opinion on nutrient requirements and dietary intakes of infants and young children in the European Union

Objective: This paper re-evaluates the requirements for iodine during pregnancy, lactation and the neonatal period, and formulates original proposals for the median concentrations of urinary iodine (UI) that indicate optimal iodine nutrition during these three critical periods of life. This paper also discusses the measurements that are used to explore thyroid functions during the same periods. Design: An extensive and critical review of the literature on thyroid physiopathology during the perinatal period. Setting: Human studies conducted in various regions throughout the world. Subjects: Pregnant women, lactating women, and newborns. Results: The following proposals are made after extensive review of the literature: the requirement for iodine by the mother during pregnancy is 250-300 mg day -1 ; during lactation the requirement is 225-350 mg day -1 ; and during the neonatal period the requirement of the infant is 90 mg day -1 . The median UI that indicates an optimal iodine nutrition during these three periods should be in the range of 150-230 mg day -1 . These figures are higher than recommended to date by the international agencies. Conclusions: Pregnantwomenandyounginfants,butespeciallythesecondgroup,are more sensitive to the effects of an iodine deficiency (ID) than the general population because their serum thyroid-stimulating hormone (TSH) and thyroxine are increased and decreased, respectively, for degrees of ID that do not seem to affect thyroid function in the general population. Systematic neonatal thyroid screening using primaryTSHcouldbethemostsensitiveindicatortomonitortheprocessofIDcontrol.

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Iodine requirements during pregnancy, lactation and the neonatal period and indicators of optimal iodine nutrition

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. © European Food Safety Authority, 2014

Scientific Opinion on Dietary Reference Values for iodine.

odine of maternal origin is required for brain development of the progeny during fetal and early postnatal life. Therefore, the iodine requirements of the mother are increased during pregnancy and lactation. This paper reevaluates the iodine requirements during pregnancy, lactation and the neonatal period and formulates original proposals for the median concentrations of urinary iodine indicating optimal iodine nutrition during these three critical periods of life. Based on an extensive and critical review of the literature on thyroid physiopathology during the perinatal period, the following proposals are made: the iodine requirements are 250-300 μg/day during pregnancy, 225-350 μg/day during lactation and 90 μg/day during the neonatal period. The median urinary iodine indicating optimal iodine nutrition during these three periods should be in the range 150-230 μg/L. These figures are higher than those recommended so far by international agencies.

Optimal iodine nutrition during pregnancy, lactation and the neonatal period

Iodine deficiency is well documented in Belgium in adults including pregnant women, adolescents, schoolchildren, and neonates, but no data are available in the age group 6 months–3 years. We investigated the status of iodine nutrition in 111 healthy subjects in this age group in an attempt to evaluate the risk of brain damage due to iodine deficiency in Belgium. In 244 casual urine samples collected in these subjects, the median concentration of iodine was 101 μg/l vs 180–220 μg/l under normal conditions. The daily supplementation of the subjects with a physiological dose of 90 μg iodine was followed by a slow and progressive increase of urinary iodine, which reached a normal level only after a delay of about 30 weeks of therapy. This observation suggests that part of the supplement of iodine offered to the children was stored in their thyroid glands until the iodine content of the gland had reverted to normal, reflecting the state of hyperavidity of the thyroid for iodide characteristic of iodine deficiency. In conclusion, infants and young children in Belgium are as iodine deficient as all other age groups of the population and, consequently, are at risk of brain damage. This works further illustrates the need for systematic iodine supplementation of the population in Belgium.

Michèle Pilchen

Papers

Iodine deficiency during infancy and early childhood in Belgium: does it pose a risk to brain development?