Effect of zinc supplementation on morbidity and growth in hospital-born, low-birth-weight infants

Abstract

Background: Low-birth-weight infants may have impaired zinc status, but little is known about the effect of zinc supplementation. Objective: The objective was to investigate the effect of daily zinc supplementation on morbidity and anthropometric status in hospital-born, low-birth-weight infants. Design: In a double-blind, randomized, placebo-controlled trial, 2052 hospital-born term infants with a birth weight ≤2500 g were randomly assigned to receive zinc or placebo. The zinc group received elemental zinc: 5 mg/d for those infants between ages 2 wk and 6 mo and 10 mg/d for those infants aged >6 mo. All-cause hospitalizations, prevalence of diarrhea, acute lower respiratory tract infections, visits to health care providers, weights, and lengths were ascertained at 3, 6, 9, and 12 mo of age. Results: The supplement was consumed for >85% of the follow-up period. Mean plasma zinc at 12 mo of age was higher in the zinc group (100.2 μg/dL) than in the control group (73.3 μg/dL) (difference in means: 26.9; 95% CI: 19.6, 34.2). The 24-h and 7-d prevalence of diarrhea and acute lower respiratory tract infections was similar at 3, 6, 9, and 12 mo. Care-seeking for illness was significantly lower in the zinc group (difference in proportions: -5.7; 95% CI: -9.9, -1.4; P < 0.05) at 9 mo. The numbers of hospitalizations, weights, and lengths were all similar at all 4 assessments. Conclusion: Hospital-born, term, low-birth-weight infants do not seem to benefit substantially from zinc supplementation that meets the Recommended Dietary Allowance for zinc in terms of morbidity or physical growth during infancy in this setting.