Lack of hemoglobin response to iron supplementation in anemic mexican preschoolers with multiple micronutrient deficiencies.

BACKGROUND In developing countries, incomplete resolution of anemia with iron supplementation is often attributed to poor compliance or inadequate duration of supplementation, but it could result from deficiencies of other micronutrients. OBJECTIVE Our objective was to assess children's hematologic response to supervised, long-term iron supplementation and the relation of this response to other micronutrient deficiencies, anthropometry, morbidity, and usual dietary intake. DESIGN Rural Mexican children aged 18-36 mo (n = 219) were supplemented for 12 mo with either 20 mg Fe, 20 mg Zn, both iron and zinc, or placebo. Children were categorized as iron-unsupplemented (IUS; n = 109) or iron supplemented (IS; n = 108). Hemoglobin, hematocrit, mean corpuscular volume, mean cell hemoglobin, plasma concentrations of micronutrients that can affect hematopoiesis, anthropometry, and diet were assessed at 0, 6, and 12 mo; morbidity was assessed biweekly. RESULTS At baseline, 70% of children had low hemoglobin (</=115 g/L), 60% had low hematocrit, 48% were ferritin deficient, 10% had deficient and 33% had low plasma vitamin B-12 concentrations, 29% had deficient vitamin A concentrations, and 70% had deficient vitamin E concentrations. Iron supplementation increased ferritin from 11 +/- 14 microg/L at baseline to 31 +/- 18 microg/L after 6 mo (P < 0.001) and 41 +/- 17 microg/L after 12 mo. However, anemia persisted in 30% and 31% of supplemented children at 6 and 12 mo, respectively, and was not significantly different between the IUS and IS groups at 12 mo. Initial plasma vitamin B-12, height-for-age, and dietary quality predicted the hematopoietic response to iron. CONCLUSION Lack of hemoglobin response to iron was associated with indicators of chronic undernutrition and multiple micronutrient deficiencies.