Iron-fortified formula milk may impair cognition during adolescence
The use of iron-fortified formula milk in infants between 6–12 months of age may lead to poorer cognitive outcomes, a recent study has shown.
Six-month-old infants were randomly assigned to receive either iron-fortified (n=216, mean gestational age, 39.4±1.1 weeks; 45.8 percent male) or low-iron (n=189, mean gestational age, 39.4±1.1 weeks; 47.1 percent male) formula milk. Cognitive ability, visual memory and perceptual ability, comprehension, vocabulary, and achievement in math were assessed at 16 years of age. The feeding trial lasted for 6 months. Those with major congenital abnormalities were excluded.
Less than half (49 percent) of the participants were assessed for outcomes at 16 years of age. At follow-up, haematologic and iron status measures were comparable between feeding groups.
Scores in eight of nine cognitive tests administered were lower in those who received iron-fortified formula during infancy. For instance, scores in the copy (adjusted difference, –0.6, 95 percent CI, –1.5 to 0.2; p=0.16) and memory (adjusted difference, –1.7, –3.2 to –0.3; p=0.02) domains of the Rey-Osterrieth complex figure test were lower in the iron-fortified arm.
Nominal between-group differences were likewise observed for the verbal similarities domain of IQ, reading vocabulary, and results in the Test of Visual Motor Integration and its supplemental test of motor coordination.
Moreover, the iron-fortified formula-fed teens scored significantly lower in terms of arithmetic achievement (adjusted difference, –2.4, –4.5 to –0.3; p=0.02) and reading comprehension (adjusted difference, –1.1, –2.0 to –0.2; p=0.02).