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 percent of infants in the iron-fortified group met criteria for iron deficiency.
The authors also found that 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.
"In conclusion, 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 study authors write. "Optimal amounts of iron in infant formula warrant further study."
In an accompanying editorial, Parul Christian, Dr.P.H., M.Sc., of the Johns Hopkins Bloomberg School of Public Health, in Baltimore, writes that the importance of the study "lies in its evaluation of the long-term developmental outcomes of an early-infancy iron intervention."
He notes, however, that, "Caution is needed in generalizing the results of the follow-up study by Lozoff et al, which stands, as yet, alone in showing small-sized negative consequences on developmental outcomes among iron-sufficient children exposed to iron-fortified vs. low-iron formula during infancy.
"Whether iron deficiency in infancy, manifest largely due to deficiency in utero, can be overcome with supplementation during infancy
|Contact: Shantell M. Kirkendoll|
University of Michigan Health System