Respiratory infections reduce the growth response to vitamin A supplementation in a randomized controlled trial

Background Studies on the effect of vitamin A supplementation on growth hav e yielded various results. It is possible that such growth is dependent on the burden of infectious diseases in the population. Methods We analysed data from a randomized, double-masked, placebo-controll ed trial to examine the role of respiratory infections and diarrhoea in mod ifying the growth response to vitamin A supplementation. A single high dose of vitamin A or placebo was given every 4 months to 1405 children aged 6-4 8 months, and 4430 child treatment cycles were used in this analysis. Results Vitamin A supplementation modestly improved linear but not ponderal growth of children who experienced little respiratory infection and especi ally of those who had vitamin A intake below the normative requirement (<40 0 RE/day). Children who received vitamin A and were free of respiratory inf ection grew 0.22 cm/4 months (95% CI:0.08, 0.37) more in height than the pl acebo group, but those with greater than or equal to 21.5% of days of respi ratory infection did not show a significant growth response to vitamin A su pplementation. Children who experienced no respiratory infection and had vi tamin A intake <400 RE/day benefited most, gaining 0.31 cm/4 months (95% CI :0.10, 0.52) more in height compared to the placebo group. Diarrhoea was as sociated with poorer growth, but did not significantly modify the effect of vitamin A supplementation on growth. Conclusions Vitamin A supplementation improves the linear growth of childre n who have a low intake of vitamin A but this impact is muted with increasi ng levels of respiratory infections.