ABSTRACT
Objectives: To evaluate the relationship between micronutrient status during infancy and middle childhood on cognition at middle childhood. Methods: A longitudinal study was conducted in apparent healthy children in the northeast of Thailand. Intelligence Quotient (IQ) was measured using the Wechsler Intelligence Scale for Children, III (Thai) at 9 y. Hemoglobin, serum ferritin, and serum zinc (sZn) were assessed at early infancy (4 mo), late infancy (1 y), and middle childhood (9 y). Serum transferrin receptor and urine iodine (UI) were assessed at 9 y. Using multiple regression, the relationship between micronutrient status during infancy and middle childhood and cognition at middle childhood was ascertained. Results: Full scale IQ and performance IQ at 9 y was influenced by sZn at 1 y (β = 0.4 μmol/L, p = 0.011 and β = 0.6 μmol/L, p = 0.001). The influence of UI at 9 y on Verbal IQ at 9 was small but significant (β = 0.02 μg/L, p = 0.024). None of the iron status at 4 mo, 1 y, and 9 y were associated with IQ. Conclusions: In apparent healthy children, zinc status at late infancy and iodine status at middle childhood were associated with IQ at middle childhood. Further analyses are needed to understand this relationship.