Infant iodine supplementation and motor and cognitive development: a randomized controlled trial

Abstract

The efficacy of two strategies to correct iodine deficiency in infants was tested in a double‐blind, randomized controlled intervention trial using oral iodized oil in a moderate‐to‐severely iodine deficient area in Morocco. Breastfeeding mother‐infant pairs (n=240) enrolled at <1 mo after birth received: 1) 400 mg iodine to the mother and placebo to the infant or; 2) placebo to the mother and 100 mg iodine to the infant. Iodine and thyroid status were measured at baseline, 3, 6, 9 mo and motor and cognitive development were measured at 12 and 18 mo (Bayley Scales of infant development II). Both interventions improved urinary iodine concentrations and thyroid function in infants (p<0.05). Iodine supplementation to the mother improved the median breast milk iodine concentration (P<0.05). At 12 mo the median Psychomotor Development Index (PDI) and Mental Development Index (MDI) in group 1 and 2 were 97 to 95 (PMI) (p = 0.46) and 101 to 105 (MDI) (p = 0.76), respectively. The data at 18 mo are currently being analyzed. Direct and indirect iodine supplementation appears equally effective in improving the iodine status, thyroid status and motor/cognitive development in breastfed infants. This study was funded by the Laboratory of Human Nutrition, ETH Zurich, Switzerland.