Routine iron fortification of infant formula linked to poor development

A long-term study examining iron-fortified vs. low-iron infant formula suggests that infants with high haemoglobin levels who received iron fortified infant formula have poorer long-term developmental outcomes.

The study was published online ahead of print in the Archives of Paediatrics & Adolescent Medicine.

“The high prevalence of iron deficiency in infancy has led to routine iron fortification of infant formula and foods in many countries,” says Betsy haemoglobin, MD, a behavioural paediatrician 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 anaemia and iron deficiency without anaemia. However, the optimal amount of iron in such products, especially infant formula, is debated,” she says.

Iron deficiency anaemia affects roughly 25 per cent of the world’s babies. Some have iron deficiency anaemia, in which a lack of iron causes problems with haemoglobin - the compound that red blood cells use to transport oxygen through the bloodstream.

Lozoff has conducted award-winning research on functional development and iron deficiencies for more than 25 years in India, Costa Rica and Chile. Iron deficiency is most common single nutrient deficiency.

The latest study provides an update on 835 healthy, full-term infants living in urban areas around Santiago, Chile. They were randomised in the trial at six months of age to receive formula with or without iron.

The 10-year assessment conducted in the U-M study included 473 children and researchers measured IQ, spatial memory, arithmetic achievement, visual-motor integration, visual perception and motor functioning.

Compared with 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 anaemia. 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 haemoglobin levels at 6 months of age had lower 10-year scores if they had received the iron-fortified formula, but those with the lowest six-month haemoglobin levels had higher scores.

“In conclusion, this study indicates poorer long-term developmental outcome in infants with high haemoglobin concentrations who received formula fortified with iron at levels currently used in the United States,” the authors write. “Optimal amounts of iron in infant formula warrant further study.”

In an accompanying editorial, Parul Christian, Dr PH, MSc, 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 Logoff 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 for improving central nervous system development and function needs to be further examined in rigorous studies of short and long duration,” he writes.

Additional authors: Katy M Clark, MA, U-M Center for Growth and Human Development; Marcela Castillo, PhD, Institute of Nutrition and Food Technology, University of Chile, JP Alessandri, Chile; Julia B Smith, EdD, Oakland University, Rochester, Mich.

Reference:  Archives of Pediatrics & Adolescent Medicine, Nov. 7, 2011, doi:10.1001/archpediatrics.2011.203.

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