The effect of daily zinc and/or multivitamin supplements on early childhood development in Tanzania: results from a randomized controlled trial

Abstract

Impaired childhood development has lifelong consequences for educational attainment and wage‐earning potential. Micronutrient supplements have the potential to improve development. The objective of this study was to determine the effect of daily zinc and/or multivitamin (vitamins C, E and B‐complex) supplements on development among Tanzanian infants. In this randomized, 2 × 2 factorial, double‐blind trial, 2400 infants were randomized to zinc (Zn), multivitamins (MV), zinc and multivitamins (Zn + MV) or placebo at 6 weeks of age. At approximately 15 months, a sub‐sample of 247 children underwent developmental assessment using the cognitive, language (receptive and expressive) and motor (fine and gross) scales of the Bayley Scales of Infant and Toddler Development Third Edition (BSID‐III). Mean BSID‐III scores were compared using univariate and multivariate linear regression models adjusted for child's sex, post‐conceptual age and test administrator. Logistic regressions were used to assess odds of low developmental scores. We did not detect a significant difference in mean BSID‐III scores in any of the five domains in univariate or multivariate models comparing each of the four treatment groups. We also did not detect a significant difference in mean BSID‐III scores when comparing children who received zinc supplements versus those who did not, or in comparisons of children who received multivitamin supplements versus those who did not. There was no significant difference in odds of a low BSID‐III score in any of the five domains in treatment arms either. Because neither daily zinc nor multivitamin (vitamins B‐complex, C and E) supplementation led to improvements in any of the developmental domains assessed using the BSID‐III, we recommend pursuing alternative interventions to promote early childhood development in vulnerable populations. © 2016 John Wiley & Sons Ltd