Breast-feeding and anemia: let's be careful.

T he study of anemia and iron deficiency in 9-month-old James Bay Cree infants reported in this issue (page 323) 1 raises 2 interesting and provocative questions. First, what is anemia in this age group? Second , how well is a breast-fed 9-month-old infant protected against iron deficiency? Commonly used norms were derived from populations of nonindigenous white children living near sea level, 2 but these cutoff points do not appear to apply to all populations. Emond and colleagues 3 found that, for British children, a more representative cutoff for anemia was a he-moglobin concentration of less than 97 g/L. Other investigators 4 found that African-Americans may have a mean he-moglobin level that is 5 g/L lower than the mean for white people, although care should be exercised in drawing conclusions from these differences. 5 In the current study, only 5.3% of the formula-fed infants, most of whom received iron-enriched formula, had hemoglobin concentrations below 105 g/L at 9 months of age, and none had significant microcytosis. Might the levels for this group of formula-fed infants represent a " normal " range for James Bay Cree in-fants? In contrast, both breast-fed babies and those fed cow's milk had findings suggestive of iron deficiency. A total of 31% of the breast-fed infants had hemoglobin levels below 105 g/L, and 17% had levels below 100 g/L, as compared with 5% and 1% respectively among the formula-fed babies. Furthermore, the odds ratio for microcytosis (mean cell volume less than 71 fL) was 11 times higher among the breast-fed infants than among their formula-fed counterparts. Microcytic, hypochromic anemia in these infants was most likely due to iron deficiency, although other, less likely, conditions, such as chronic disease, vitamin B 6 deficiency , lead poisoning and thalassemia minor, can give a similar picture. Increased demand for iron among breast-fed compared with formula-fed babies was not likely a factor. The mean weight gain, and, thus, the blood volume expansion with growth, was less for breast-fed infants. If anything, this should have resulted in less demand for iron and less reason for iron deficiency. Iron deficiency associated with consumption of cow's milk is well known. Iron deficiency among breast-fed infants is less well accepted, 6 yet the findings of this study suggest that it may occur by 9 months of age. A healthy baby is protected against iron deficiency during the first 6 months of life. Hemoglobin …