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

Background: In developing countries, incomplete resolution of anemia with i ron supplementation is often attributed to poor compliance or inadequate du ration of supplementation, but it could result from deficiencies of other m icronutrients. Objective: Our objective was to assess children's hematologic response to s upervised, long-term iron supplementation and the relation of this response to other micronutrient deficiencies, anthropometry, morbidity, and usual d ietary intake. Design: Rural Mexican children aged 18-36 mo (n = 219) were supplemented fo r 12 mo with either 20 mg Fe, 20 mg Zn, both iron and zinc, or placebo. Chi ldren were categorized as iron-unsupplemented (IUS; n = 109) or iron supple mented (IS; n = 108). Hemoglobin, hematocrit, mean corpuscular volume, mean cell hemoglobin, plasma concentrations of micronutrients that can affect h ematopoiesis, anthropometry, and diet were assessed at 0, 6, and 12 mo; mor bidity was assessed biweekly. Results: At baseline, 70% of children had low hemoglobin (less than or equa l to 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 defi cient vitamin A concentrations, and 70% had deficient vitamin E concentrati ons. Iron supplementation increased ferritin from 11 +/- 14 mu g/L at basel ine to 31 +/- 18 mu g/L after 6 mo (P < 0.001) and 41 +/- 17 mu g/L after 1 2 mo. How ever, 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, a nd dietary quality predicted the hematopoietic response to iron. Conclusion: Lack of hemoglobin response to iron was associated with indicat ors of chronic undernutrition and multiple micronutrient deficiencies.