Growth, stunting, and micronutrient supplementation: Perspectives fromthe south-east Asia multi-country trial of iron and zinc supplementation in infants (SEAMTIZI)

Abstract

Linear growth faltering during the first 2 years of life is a common feature in most developing countries, eventually leading to stunting, meaning that height falls below two standard deviations of the reference. Stunting is associated with increased morbidity and mortality. Growth faltering is a multi-factorial process, with inadequate intakes of protein, energy, and/or micronutrients all contributing to suboptimal growth. To investigate whether inadequate intakes of iron and/or zinc contribute to growth faltering in infancy in South-East Asia, a multi-country trial was conducted between 1997 and 2000: the SEAMTIZI trial with study sites in Vietnam, Thailand, and Indonesia (two sites). In the SEAMTIZI trial, infants (mean age 5 months) received 10 mg of iron, 10 mg of zinc, 10 mg of both iron and zinc, or placebo daily for 6 months. The SEAMTIZI trial showed that blanket supplementation with iron or zinc could not prevent the progressive decrease in anthropometric Z-scores during the first year of life in SE Asia. At the end of the study, overall stunting prevalence was above 20%, although there were marked differences between the sites. Boy infants had a much higher risk of becoming stunted than girl infants. Baseline factors such as anemia and birth weight influenced the effect of supplementation, with a beneficial effect of zinc supplementation in anemic infants but no effect in non-anemic infants. As blanket supplementation with iron or zinc will not be beneficial to all recipients, and may have adverse effects in some, underlying mechanisms and baseline factors need to be identified to allow targeting only those who may benefit. Development of a multi-factorial approach to prevent growth faltering rather than a search for a single micronutrient that does it all, a 'Golden bullet,' is urgently needed.