Effect of zinc supplementation on development and growth of Chilean infants

Objective: To evaluate the effect of zinc supplementation on growth and development during infancy. Design: We randomized 150 term neonates of low socioeconomic status to receive supplemental zinc 5 mg/d (SG) or a lactose placebo (PG); 112 completed a 1-year follow-up. All were breast-fed and given cow milk formula after weaning; solid foods and iron were added at 5 months. Anthropometry measured monthly, psychomotor development (PDI), mental development (MDI), and behavior including motor quality factor were assessed by Bayley Scales at 6 and 12 months. The groups were comparable in maternal characteristics, birth weight, home environment, and mother-infant interaction. Results: No effects of zinc on weight, length, and weight for length at 12 months were found controlling for sex and breast-feeding. The mean PDI (SG: 84.5 +/- 11.5 vs PG: 87.6 +/- 9.9) and MDI (90.9 +/- 10.5 vs 85.9 +/- 9.1) were similar; however, 46 of 52 infants in the PG scored <100 in MDI vs 42 of 57 in the SG (P <.05). A smaller proportion of the SG, 2 of 57, scored low in motor quality factor at 6 months compared with the PG, 8 of 52 (P =.02). The mean at 12 months for the SG was 31.9 +/- 2.8 and for the PG 30.8 +/- 2.9 (P <.05); zinc supplementation entered the multiple regression at 12 months (P = .037. Conclusions: Zinc supplementation may have a beneficial effect on mental development and motor quality behavior of healthy term infants.