Association between Elevated Iodine Intake and IQ among School Children in Portugal

• Type: Article in International Scientific Journal
• Date: 2022

Authors

IP Carvalho (Author) FMUP; Peixoto, B (Author) Other; Caldas, JC (Author) Other; Costa, A (Author) Other; Silva, S (Author) Other; Moreira, B (Author) Other; Agostinho Almeida (Author) FFUP; Moreira Rosario, A (Author) Other; Guerra, A (Author) Other; Delerue Matos, C (Author) Other; Sintra, D (Author) Other; Pestana, D (Author) Other; Pinto, E (Author) Other; Mendes, FC (Author) Other; Martins, I (Author) Other; Leite, JC (Author) Other; Fontoura, M (Author) Other; Maia, ML (Author) Other; Queiros, P (Author) Other; Moreira, R (Author) Other; Leal, S (Author) Other; Norberto, S (Author) Other; Costa, V (Author) Other; Fernandes, VC (Author) Other; Elisa Keating (Author) FMUP; Azevedo L (Author) FMUP; Calhau, C (Author) Other

Journal

Title: Nutrients

Vol. 14

Final page: 4493

ISSN: 2072-6643

Publisher: MDPI

Indexing

ISI Web of Knowledge - 2 Citations

Scopus - 3 Citations

Other information

Authenticus ID: P-00X-BG2

DOI: 10.3390/nu14214493

Abstract (EN): 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 mu g/g and >= 250 mu g/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 mu g/L; median iodine-to-creatinine ratio = 126 mu g/g) according to the WHO's criteria. A greater proportion of children in the >= 250 mu g/g group had below-average IQs, compared to children with less than 250 mu g/g (p = 0.037), despite a sizable (though non-significant) proportion of children in the less-than-250 mu g/g group also presenting below-average IQs, at the bottom of the iodine distribution (<50 mu g/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.

Language: English

Type (Professor's evaluation): Scientific

No. of pages: 11