ANN ARBOR, Mich.—A new study published online in the Archives of Pediatrics & Adolescent Medicine is raising questions about the optimal amount of iron fortification in infant formulas after results found infants with high hemoglobin levels who were fed iron-fortified infant formula had poorer long-term developmental outcomes compared to babies who received a low-iron formula.
Iron deficiency affects approximately 25% of the world’s babies, some of whom also have iron deficiency anemia that causes problems with hemoglobin—the compound that red blood cells use to transport oxygen through the bloodstream.
“The high prevalence of iron deficiency in infancy has led to routine iron fortification of infant formula and foods in many countries," said lead study author Betsy Lozoff, M.D., a behavioral pediatrician at the University of Michigan Health System and research professor at the University of Michigan Center for Human Growth and Development. “These interventions help reduce iron-deficiency anemia and iron deficiency without anemia. However, the optimal amount of iron in such products, especially infant formula, is debated."
The study provided a 10-year follow-up on 835 healthy, full-term infants living in urban areas around Santiago, Chile. They were randomized in the trial at 6 months of age to receive formula with or without iron. The follow-up assessment included 473 children and researchers measured IQ, spatial memory, arithmetic achievement, visual-motor integration, visual perception and motor functioning. Compared to the low-iron group, the iron-fortified group scored lower on every 10-year outcome measured.
Of the seven tests administered at the 10-year follow-up, two (spatial memory and VMI) showed statistically significant lower scores in the iron-fortified group compared to the low-iron group, and four (IQ, visual perception, motor coordination and arithmetic achievement) showed suggestive trends that did not reach statistical significance. No statistically significant differences were found in iron status at 10 years, and only one child had iron-deficiency anemia. Less than 10% of infants in the iron-fortified group met criteria for iron deficiency.
The researchers found children with the highest hemoglobin levels at 6 months of age had lower 10-year scores if they had received the iron-fortified formula, but those with the lowest 6-month hemoglobin levels had higher scores.
“This study indicates poorer long-term developmental outcome in infants with high hemoglobin concentrations who received formula fortified with iron at levels currently used in the United States," the researchers said. “Optimal amounts of iron in infant formula warrant further study."
