1. Association between Elevated Iodine Intake and IQ among School Children in Portugal
- Author
-
Irene P. Carvalho, Bruno Peixoto, José Carlos Caldas, Ana Costa, Sofia Silva, Bárbara Moreira, Agostinho Almeida, André Moreira-Rosário, António Guerra, Cristina Delerue-Matos, Diana Sintra, Diogo Pestana, Edgar Pinto, Francisca Castro Mendes, Inês Martins, João Costa Leite, Manuel Fontoura, Maria Luz Maia, Pedro Queirós, Roxana Moreira, Sandra Leal, Sónia Norberto, Vera Costa, Virgínia Cruz Fernandes, Elisa Keating, Luís Azevedo, and Conceição Calhau
- Subjects
excessive iodine ,cognition ,school ages ,iodine-adequate population ,representative sample ,Nutrition. Foods and food supply ,TX341-641 - Abstract
The goal of this work was to examine whether elevated iodine intake was associated with adverse effects on IQ among school-age children in Portugal. In a representative sample of children from the north of the country, IQ percentiles by age (assessed with Raven’s Colored Progressive Matrices) were dichotomized to N = 1965) was classified as generally iodine-adequate (median urinary iodine concentration = 129 µg/L; median iodine-to-creatinine ratio = 126 µg/g) according to the WHO’s criteria. A greater proportion of children in the ≥250 µg/g group had below-average IQs, compared to children with less than 250 µg/g (p = 0.037), despite a sizable (though non-significant) proportion of children in the less-than-250 µg/g group also presenting below-average IQs, at the bottom of the iodine distribution (p = 0.047). The association remained significant after the adjustment for confounders, with the elevated iodine group showing increased odds of having below-average IQs when compared with the non-elevated iodine group (OR 1.55; 95% CI 1.11–2.17; p = 0.011). Consistently, the former group presented a lower mean IQ than the latter (p = 0.006). High iodine intake was associated with lower IQs even in a population classified as iodine-adequate. These results bear on child cognition and on initiatives involving iodine supplementation.
- Published
- 2022
- Full Text
- View/download PDF