Data from a recent study published in The Lancet show that iodine supplementation in breastfeeding mothers can ensure iodine sufficiency in their infants for at least six months through breastfeeding. Raschida Bouhouch, PhD, of the Laboratory of Human Nutrition in Zurich, and colleagues noted that this route can safely and rapidly restore normal thyroid function in infants. The researchers evaluated 241 pairs of mothers and infants for urinary iodine, breast milk iodine, thyroid stimulating hormone levels, free thyroxine levels, and infant development. Mothers and infants were divided into 2 groups: an indirect infant supplementation group (n=121), in which mothers received iodinated oil (containing 400 mg of iodine) and infants received placebo; and a direct supplementation group (n=118 ), in which infants received iodinated oil (containing 100 mg of iodine) and mothers received placebo. The median urinary iodine concentration level at baseline was 35 μg/L for the mother and 73 μg/L for the infant, defined as iodine deficiency. Compared to the direct supplementation group, urinary iodine (P=0.011), breast milk iodine (P<0.0001) and infant urinary iodine concentration (P=0.042) were higher in the indirect supplementation group for mothers. There were no significant differences in maternal TSH (P=0.276) and T4 (P=0.074) levels, and infant TSH (P=0.597) and T4 (P=0.184) levels between the two groups throughout the study period. However, the researchers reported a lower number of infants with hypothyroidism in the indirect supplementation group compared to the direct supplementation group (P = 0.023). Median urinary iodine concentrations were adequate (>100 μg/L) in infants in the indirect supplementation group at 3 and 6 months of age. However, urinary iodine concentrations in infants in the direct supplementation group were adequate only at 6 months of age. In an accompanying journal review, Sarah C. Bath, a postdoctoral researcher at Surrey University, UK, writes that iodine deficiency in the early stages of life can lead to cognitive impairment in children and is associated with infant mortality. Iodine is essential for the synthesis of thyroid hormones, and because thyroid hormones play a role in brain development, it is particularly important that infants and children have adequate iodine nutrition during pregnancy, lactation and after birth. The World Health Organization (WHO) recommends that mothers consume 250 μg of potassium iodide daily or 400 mg of iodized oil orally each year while breastfeeding, and recommends exclusive breastfeeding for at least the first six months of life. Researcher Dr. Bouhouch noted that the WHO’s recommended dose of iodine supplementation may be inadequate and needs to be adjusted. Dr. Elizabeth N. Pearce, Associate Professor of Medicine at Boston University School of Medicine, commented, “Adequate iodine intake is critical for normal neurodevelopment in infants and children, so the data provided by this study are important in confirming that recommending iodine supplementation to nursing mothers with moderate to severe iodine deficiency is an effective public health strategy to ensure the iodine nutritional status of infants through breastfeeding. Iodine nutritional status of the infant. In the United States, pregnant women are generally mildly iodine deficient, so the American Thyroid Association (ATA) recommends that women who are pregnant or breastfeeding should take 150 μg of iodine supplements daily.”