Iodine Boosts Childhood Intelligence
Objective: The objective was to determine whether supplementing mildly iodine-deficient children with iodine improves cognition.
Design: A randomized, placebo-controlled, double-blind trial was conducted in 184 children aged 10–13 y in Dunedin, New Zealand. Children were randomly assigned to receive a daily tablet containing either 150 µg I or placebo for 28 wk. Biochemical, anthropometric, and dietary data were collected from each child at baseline and after 28 wk. Cognitive performance was assessed through 4 subtests from the Wechsler Intelligence Scale for Children.
Results: At baseline, children were mildly iodine deficient [median urinary iodine concentration (UIC): 63 µg/L; thyroglobulin concentration: 16.4 µg/L]. After 28 wk, iodine status improved in the supplemented group (UIC: 145 µg/L; thyroglobulin: 8.5 µg/L), whereas the placebo group remained iodine deficient (UIC: 81 µg/L; thyroglobulin: 11.6 µg/L). Iodine supplementation significantly improved scores for 2 of the 4 cognitive subtests [picture concepts (P = 0.023) and matrix reasoning (P = 0.040)] but not for letter-number sequencing (P = 0.480) or symbol search (P = 0.608). The overall cognitive score of the iodine-supplemented group was 0.19 SDs higher than that of the placebo group (P = 0.011).
Conclusions: Iodine supplementation improved perceptual reasoning in mildly iodine-deficient children and suggests that mild iodine deficiency could prevent children from attaining their full intellectual potential.
Rosie C Gordon, Meredith C Rose, Sheila A Skeaff, Andrew R Gray, Kirstie MD Morgan and Ted Ruffman.
Iodine supplementation improves cognition in mildly iodine-deficient children
Am J Clin Nutr
Departments of Human Nutrition, Preventive and Social Medicine, and Psychology, University of Otago, Dunedin, New Zealand.