Impact of Nutritional Interventions on Mental Development of Children Under-two in Developing Countries: A Systematic Review of Randomized Controlled Trials
Leila Larson *
Emory University, Atlanta, Georgia, USA.
Aisha Yousafzai
Aga Khan University, Karachi, Sindh, Pakistan.
*Author to whom correspondence should be addressed.
Abstract
Objectives: High levels of early child malnutrition in developing countries are of concern not only because they affect later growth but because they may affect mental and motor development. This systematic review updates and goes beyond previous ones by answering two important questions: 1) are effects on mental development associated with indicators of nutritional change; and 2) are effects on mental development associated with improvement in motor development?
Methods: Our systematic review of articles on Medline, PsycINFO, and Global Health was limited to randomized trials in developing countries, with mental development of children from birth to age two as an outcome. The initial yield of 1740 studies was reduced to 24.
Results: Of the 17 postnatal and 7 prenatal nutritional interventions, the majority used zinc, iron/folic acid, vitamin A or multiple micronutrients, with a few evaluating fatty acids. Most studies used groups that were comparable at baseline; most used the Bayley Mental and Motor tests. The mean (range) effect size (d) for postnatal and prenatal nutritional interventions on mental development was 0.12(-0.56 to 1.1) and 0.002(-0.31 to 0.19), respectively. Among the postnatal interventions, the percentage (number) of studies with an effect size above 0.1 for weight-for-age and height-for-age was 27% (3) and 33% (4), respectively. Motor development fared better with an effect size of 0.19(-0.29 to 1.28).
Conclusions: In summary, nutritional interventions had small effects on mental development. They might have greater effect if they addressed hygiene and sanitation, as well as macronutritional deficiencies, and were longer in duration.