Zinc supplementation improved length growth only in anemic infants in a multi-country trial of iron and zinc supplementation in South-East Asia.

Data from 4 randomized, placebo-controlled, double-blind trials in Indonesia, Thailand, and Vietnam, the South-East Asian Multicountry Trial on Iron and Zinc supplementation in Infants (SEAMTIZI), were pooled to investigate the effects of iron and zinc supplementation infant growth. Infants (n = 2451) aged 4-6 mo old were supplemented with iron (10 mg/d) and/or zinc (10 mg/d) for 6 mo. Overall, neither iron nor zinc supplementation prevented the progressive growth faltering during infancy, which is common in many developing countries. However, infants who received zinc were less likely to be stunted at the end of the supplementation period (odds ratio 0.80; 95% CI 0.64-1.0). Boys had a 30% higher risk of being stunted at the end of the study than girls (P 3500 g (estimated effect size, -0. 14 HAZ score; P < 0.01), but with no significant effect in infants with a lower birth weight. This study shows that blanket supplementation of infants with iron or zinc will not be beneficial to all recipients and may have adverse effects in some. Hence, interventions such as iron and zinc supplementation for infants should be restricted to subgroups in which there is a clear benefit and baseline factors should be considered and characterized before implementing new policies