Simultaneous zinc and vitamin A supplementation in Bangladeshi children: randomised double blind controlled trial

Objective To evaluate the effect of simultaneous zinc and vitamin A supplem entation on diarrhoea and acute lower respiratory infections in children. Study design Randomised double blind placebo controlled trial. Setting Urban slums of Dhaka, Bangladesh. Participants and methods 800 children aged 12-35 months were randomly assig ned to one of four intervention groups: 20 mg zinc once daily for 14 days; 200 000 IU vitamin A, single dose on day 14; both zinc and vitamin A; place bo. The children were followed up once a week for six months, and morbidity information was collected. Results The incidence and prevalence of diarrhoea were lower in the zinc an d vitamin A groups than in the placebo group. Zinc and vitamin A interactio n had a rate ratio (95% confidence interval) of 0.79 (0.66 to 0.94) for the prevalence of persistent diarrhoea and 0.80 (0.67 to 0.95) for dysentery. Incidence (1.62; 1.16 to 2.25) and prevalence (2.07; 1.76 to 2.44) of acute lower respirator,,, infection were significantly higher in the zinc group than in the placebo group. The interaction term had rate ratios of 0.75 (0. 46 to 1.20) for incidence and 0.58 (0.46 to 0.73) for prevalence of acute l ower respiratory infection. Conclusions Combined zinc and vitamin A synergistically reduced the prevale nce of persistent diarrhoea and dysentery. Zinc was associated with a signi ficant increase in acute lower respiratory infection, but this adverse effe ct was reduced by the interaction between zinc and vitamin A.