Iodine status, dietary iodine intake and iodized salt in school-aged children in São Miguel Island, Azores, Portugal

Abstract

Objective: School-aged children in São Miguel Island, Azores, Portugal, are a population with a long history of iodine deficiency, and a recent governmental program for iodized salt (IS) consumption was implemented. This study investigated urinary iodine concentration (UIC), household and school IS consumption, and iodine-rich food intake in school-aged children.

Methods: In this cross-sectional study, spot urine samples and dietary iodine intake were collected. Urinary iodine concentration was evaluated using the fast colorimetric method. Dietary iodine intake was calculated by determining the iodine content of reported food intake using a Food Frequency Questionnaire (FFQ).

Results: The median UIC was 106.7 µg/L, and 55.5% of children had UIC >100 µg/L. Iodized salt was used by 100% of schools and 48.3% of school-aged children's households. Excluding iodine in IS, the median dietary iodine intake was 105.5 µg/d. No significant correlation was found between UIC and dietary iodine intake. Milk and dairy products, with a median intake of 311.1 g/d, provided 81.5 µg iodine/d. Seafood, with a median intake of 30.5 g/d, provided 16.8 µg iodine/d. Dairy product intake was not statistically correlated with UIC (P = 0.567).

Conclusions: School-aged children in São Miguel Island did not have iodine deficiency after the governmental program for IS consumption. Adequate iodine status of school-aged children probably reflects not only an increase in iodine intake, through IS, but also an improvement of food intake patterns. Future studies are needed to ensure the sufficient iodine status of school-aged children in the Azores, and political commitment and efforts are required to prevent the possible reemergence of iodine deficiency.

Keywords: Azorean Islands; Children; Dietary intake; Iodine; São Miguel.