Direct iodine supplementation of infants versus supplementation of their breastfeeding mothers: a double-blind, randomised, placebo-controlled trial



Iodine deficiency in infants can damage the developing brain and increase mortality. Present recommendations state that oral iodised oil should be given to breastfeeding mothers to correct iodine deficiency in infancy when iodised salt is not available, and that direct supplementation should be given to infants who are not being breastfed or receiving iodine-fortified complimentary foods. However, there is little evidence for these recommendations. We aimed to assess the safety and efficacy of direct versus indirect supplementation of the infant.


We did this double blind, randomised, placebo-controlled trial in Morocco. Healthy breastfeeding mothers and their term newborn babies (aged ≤8 weeks) were block randomised by clinic day to receive either: one dose of 400 mg iodine to the mother and placebo to the infant (indirect infant supplementation), or one dose of about 100 mg iodine to the infant and placebo to the mother (direct infant supplementation). Randomisation was masked to participants and investigators. Coprimary outcomes were: maternal and infant urinary iodine concentrations, breastmilk iodine concentration, maternal and infant thyroid-stimulating hormone (TSH) concentrations, maternal and infant thyroxine (T4) concentrations, and infant growth. These outcomes were measured at baseline, and when infants were aged about 3 months, 6 months, and 9 months, and the two groups were compared using mixed effects models. This study is registered with, number NCT01126125.


We recruited 241 mother-infant pairs between Feb 25, and Aug 10, 2010, and completed data collection by Aug 6, 2011. At baseline, median urinary iodine concentration was 35 μg/L (IQR 29-40) in mothers and 73 μg/L (29-237) in infants, suggesting iodine deficiency. During the study, maternal urinary iodine concentration (p=0·011), breastmilk iodine concentration (p100 μg/L), whereas infant urinary iodine concentration was sufficient only at 6 months in the direct supplementation group. There were no serious adverse events in either group.


In regions of moderate-to-severe iodine deficiency without effective salt iodisation, lactating women who receive one dose of 400 mg iodine as oral iodised oil soon after delivery can provide adequate iodine to their infants through breastmilk for at least 6 months, enabling the infants to achieve euthyroidism. Direct supplementation is less effective in improving infant iodine status.



Alex's notes: This is just more frosting on the cake supporting the notion that maternal dietary habits are CRUCIAL to proper fetal development. Breast milk is an incredible substance that provides everything a baby human needs to develop during a time when development is most rapid. While I don't think it is necessary to supplement with everything on the market, pregnant women should be extra concious of their dietary habits and aim to eat a diverse spectrum of foods. This includes vegetables of all colors, seafoods, meats (especially organ meats), and healthy fats (especially DHA).

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