Intelligence Quotient and Iodine Intake: A Cross-Sectional Study in Children
Piedad Santiago-Fernandez,
Rosario Torres-Barahona,
J. Antonio Muela-Martínez,
Gemma Rojo-Martínez,
Eduardo García-Fuentes,
M. José Garriga,
Ana García León and
Federico Soriguer
Unidad de Endocrinología, Complejo Hospitalario Ciudad de Jaén (P.S.-F.), 23007 Jaén, Spain; Departamento de Psicología, Universidad de Jaén (R.T.-B., J.A.M.-M., A.G.L.), 23071 Jaén, Spain; and Servicio de Endocrinología y Nutrición, Complejo Hospitalario Carlos Haya (G.R.-M., E.G.-F., M.J.G., F.S.), 29009 Málaga, Spain
Address all correspondence and requests for reprints to: Dr. F. Soriguer, Servicio de Endocrinología y Nutrición, Hospital Civil, Complejo Hospitalario Carlos Haya, Plaza del Hospital Civil s/n, 29009 Málaga, Spain. E-mail: federico.soriguer.sspa{at}juntadeandalucia.es.
The association between iodine deficiency and poor mental andpsychomotor development is known. However, most studies wereundertaken in areas of very low iodine intake. We investigatedwhether a similar association is found in schoolchildren fromsouthern Europe with a median urinary iodine output of 90 µg/liter.Urinary iodine levels were measured in 1221 children who alsocompleted a questionnaire about their usual dietary habits.Intelligence quotient (IQ) was measured by Cattell’s gfactor test. IQ was significantly higher in children with urinaryiodine levels above 100 µg/liter. The risk of having anIQ below the 25th percentile was significantly related to theintake of noniodized salt and drinking milk less than once aday. As expected, the risk of having an IQ below 70 was greaterin children with urinary iodine levels less than 100 µg/liter.In conclusion, this study demonstrates that the IQ of schoolchildrenin a developed country can be influenced by iodine intake. Theresults support the possibility of improving the IQ of manychildren from areas with mild iodine deficiency by ensuringan iodine intake sufficient to achieve a urinary iodine concentrationgreater than 100 µg/liter.
This work was supported in part by a grant from the Junta deAndalucía (SAS 124/02) and funds from the MaimónidesAssociation. The investigation group belongs to the Red de Centrosde Metabolismo y Nutrición (RCMN, C03/08) of the Institutode Salud Carlos III.
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