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Author(s): Carvalho, IP
Peixoto, B
Caldas, JC
Costa, A
Silva, S
Moreira, B
Almeida, A
Moreira-Rosário, A
Guerra, A
Delerue-Matos, C
Sintra, D
Pestana, D
Pinto, E
Mendes, FC
Martins, I
Leite, JC
Fontoura, M
Maia, ML
Queirós, P
Moreira, R
Leal, S
Norberto, S
Costa, V
Fernandes, VC
Keating, E
Azevedo, L
Calhau, C
Title: Association between Elevated Iodine Intake and IQ among School Children in Portugal
Publisher: MDPI
Issue Date: 2022
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 <50 (“below-average” IQs) and ≥50. Morning urine iodine concentrations, corrected for creatinine, were dichotomized to <250 µg/g and ≥250 µg/g, according to the European Commission/Scientific Committee on Food’s tolerable upper level of daily iodine intake for young children. Data were examined with Chi-square tests, logistic regression, and GLM univariate analysis. The sample (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 (<50 µg/g). The proportion of below-average IQs increased with increasingly elevated iodine concentrations (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. © 2022 by the authors.
Subject: cognition; excessive iodine; iodine-adequate population; representative sample; school ages
Source: Nutrients. 2022 Oct 26;14(21):4493. doi: 10.3390/nu14214493.
Related Information: info:eu-repo/grantAgreement/FCT/FARH/SFRH/BPD/109158/2015/PT
info:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UIDB/50006/2020/PT
info:eu-repo/grantAgreement/FCT/6817 - DCRRNI ID/UIDP/50006/2020/PT
Document Type: Artigo em Revista Científica Internacional
Rights: openAccess
Appears in Collections:ISPUP - Artigo em Revista Científica Internacional

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