Simultaneous Weekly Supplementation of Iron and Zinc Is Associated with Lower Morbidity Due to Diarrhea and Acute Lower Respiratory Infection in Bangladeshi Infants

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Abstract
Given the high prevalence of micronutrient deficiencies and infectious diseases in infants in developing countries, an evaluation of the efficacy of different micronutrient formulations on infant morbidity is a priority. The efficacy of weekly supplementation of four different micronutrient formulations on diarrhea and acute lower respiratory infection (ALRI) morbidity was evaluated in Bangladeshi infants. In a double-blind, randomized, controlled community trial, 799 infants aged 6 mo were randomly assigned to one of the following 5 groups: 1) 20 mg elemental iron with 1 mg riboflavin, 2) 20 mg elemental zinc with 1 mg riboflavin, 3) 20 mg iron and 20 mg zinc with 1 mg riboflavin, 4) a micronutrient mix (MM) containing 20 mg iron, 20 mg zinc, 1 mg riboflavin along with other minerals and vitamins and 5) a control treatment, 1 mg riboflavin only. Health workers visited each infant weekly until age 12 mo to feed the supplement and to collect data on diarrhea and ALRI morbidity. Hemoglobin, serum ferritin and serum zinc levels of a sample of infants were measured at 6 and 12 mo. Compared with the control group, at 12 mo, serum ferritin levels were higher in the iron + zinc group, and serum zinc levels were higher in the zinc and iron + zinc groups. Simultaneous supplementation with iron + zinc was associated with lower risk of severe diarrhea, 19% lower in all infants and 30% lower in less well-nourished infants with weight-for-age Z-score below −1. Iron + zinc supplementation was also associated with 40% lower risk of severe ALRI in less well-nourished infants. MM supplementation was associated with a 15% higher risk of diarrhea in all infants and 22% higher risk in less well-nourished infants. Intermittent simultaneous supplementation with iron + zinc seems promising; it will be useful to determine whether higher doses would provide greater benefits.