Iron Supplementation and Psychomotor Performance

Abstract & Commentary

Synopsis: Substitution of an iron-supplemented formula for an unsupplemented formula at 6-9 months of age in poor, inner-city children was associated with both improved hematological status and reduced the decline in psychomotor development in the second half of the first year of life.

Source: Williams J, et al. Iron supplemented formula milk related to reduction in psychomotor decline in infants from inner city areas: Randomised study. BMJ 1999;318:693-697.

Williams and associates, from the university of Birmingham, United Kingdom, studied 100 5.7-8.6-month-old infants who were receiving non-iron-fortified cow milk formula because of the parents’ choice. This was to determine the effect on hematological and psychomotor development of changing to an iron-supplemented formula. All children had a baseline developmental assessment using the Griffith scales as well as a hematologic assessment. They were then randomized to either continue non-iron-fortified formula or switch to an iron-supplemented formula. Developmental and hematologic assessments were repeated after 18 and 24 months. There were no significant differences in hemoglobin levels at the time of randomization, but after 18 months, 33% of the children receiving iron-fortified formula were anemic compared to only 2% of the iron-supplemented group. The two groups had Griffith general quotient scores that were not significantly different at randomization. Both groups showed a decline of test scores during the study, but the decline was significantly greater in the non-iron-supplemented formula group. By 24 months, the decrease in the mean scores of the unsupplemented formula group was 14.7, compared to 9.3 in the iron-supplemented group (P < 0.02).

Comment by Howard A. Pearson, MD, FAAP

Although I am not aware of a formal meta-analysis of the many articles relating psychomotor development and iron deficiency, most studies have concluded that there is a measurable effect on behavior and learning associated with iron deficiency and iron deficiency anemia in infancy, and that this can be improved, at least in the short term, with dietary iron supplementation. One of the nutritional triumphs of the last two decades has been the marked reduction of iron deficiency anemia in U.S. children,1 and this improvement has generally been related to the increasing use of iron-fortified cow’s milk infant formulas, often through the women, infants, and children (WIC) program for poor children. Despite these kinds of findings, there remains a reluctance on the part of some pediatricians concerning the routine use of iron-fortified infant formulas. The basis of this reluctance is really a little difficult for me to understand. There are many anecdotes that relate iron therapy and GI problems (pain, constipation, etc.). These symptoms are most frequent in women. A number of stud-ies have shown no difference in GI symptoms of any sort in infants receiving iron-supplemented formula. I suspect that physician concern about GI intolerance to iron-fortified formulas is strongly age related. Older pediatricians are more likely to believe that iron-supplemented formulas are associated with GI symptoms and constipation. The younger generations of pediatricians, in my experience, usually prescribe an iron-fortified formula for infants who are not breast fed. In the study of Williams et al of poor, inner-city children in Birmingham, UK, the 33% preva-lence of iron deficiency anemia in 18- to 24-month-old infants consuming non-iron-supplemented formulas is very similar to what was seen in poor, inner-city U.S. children before the widespread introduction of the WIC pro-gram in the early 1970s. The Williams study clearly corroborates that iron supplementation is effective in preventing iron deficiency anemia. The unique finding of the Williams study was its demonstration that iron supplementation was also associated with better (or at least less deterioration of) psychomotor performance of treated children compared to nontreated children, suggesting a protective effect of iron treatment.

In another study where the effects of a novel form of iron supplementation were investigated, Adish and associates randomly divided a large group of Ethiopian infants into two groups.2 In one group, a cast-iron cooking pot was provided to the family; the other group was given an aluminum cooking pot. After 12 months of follow-up, the children receiving food cooked in iron pots had significantly lower rates of anemia and better growth than children whose food was cooked in aluminum pots. This Ethiopian study may seem a bit exotic, but I well remember my observations in poor, rural children in Florida 30 years ago. I saw very little severe iron deficiency in that population, certainly much less than I encountered in New Haven, Conn, only a few years later. I also recall that in the rural homes of these poor children that I visited, almost invariably there was a large, black cast-iron pot on the wood stove, slowly cooking greens, a dietary staple. The bottom line is that infants need some form of dietary iron supplementation by 4-6 months of age to prevent progressive iron deficiency and its hema-tological and non-hematological consequences.

References

1. Lozoff B, et al. Iron deficiency anemia and iron therapy effects on infant developmental test performance. Pediatrics 1987;79:981-995.

2. Adish AA, et al. Effect of consumption of food cooked in iron pots on iron status and growth of young children: A randomised trial. Lancet 1999;353:712-716.

Substitution of an iron-supplemented for an unsupplemented formula at 6-9 months of age to poor inner-city children:

    a. has no effect on hematological performance.
    b. is associated with an increase of gastrointestinal symptoms.
    c. is associated with a lesser decrease in psychomotor performance than that in children continuing to receive unsupplemented formulas.
    d. is nearly universally advocated by pediatricians.