Objective: To determine the effect of zinc supplementation on behaviour in low-income school aged children.
Design: Double-blind randomized, placebo controlled trial.
Setting: Low-income district primary school in Turkey.
Participants: Third grade students in the school. Among 252 students, 226 participated and 218 completed the study.
Intervention: Children in each class were randomized either to the study group to receive 15 mg/day elemental zinc syrup or to placebo group to receive the syrup without zinc for 10 weeks.
Main outcome measures: The change in Conner's Rating Scales for Teachers and Parents scores after supplementation.
Results: The mean Conner's Rating Scale for Parents scores on attention deficit, hyperactivity, oppositional behaviour and conduct disorder decreased significantly in the study and placebo groups after supplementation (p < 0.01). The prevalence of children with clinically significant parent ratings on attention deficit (p = 0.01) and hyperactivity (p = 0.004) decreased in the study group while prevalence of oppositional behaviour (p = 0.007) decreased in the placebo group. In children of mothers with low education all mean Parents' scores decreased significantly (p < 0.01) in the study group while only hyperactivity scores decreased in the placebo group (p < 0.01). In this subgroup the prevalence of children with clinically significant scores for attention deficit, hyperactivity and oppositional behaviour decreased only in the study group (p < 0.05). There was no change in mean Teachers' scores.
Conclusion: In our study zinc supplementation decreased the prevalence of children with clinically significant scores for attention deficit and hyperactivity. The affect on behaviour was more evident in the children of low educated mothers.