Impact of Zinc Supplementation on Mortality and Hospitalizations in Children Aged 1 Months to 23 Months

Objective: Studies in developing countries show substantial reduction in diarrhoea and respiratory morbidity in young children receiving zinc supplementation. The impact of daily zinc supplementation coadministered with iron folic acid in young children on all cause hospitalisation and mortality in comparison with iron folic acid alone, was evaluated to help shape public policy.

Design: Randomised double blind trial

Setting: Low to middle socio-economic urban neighbourhoods of north and north-west Delhi in India

Participants: 94359 subjects aged 1 month to 23 months

Interventions: The subjects were administered dispersible tablets containing one recommended daily allowance of zinc and iron folic acid or iron folic acid alone, daily for 12 months after enrolment.

Main outcome measures: Hospitalisations were captured through passive surveillance of eight hospitals by trained study physicians. Deaths were ascertained through bimonthly visits to households.

Results: A third of the total children had low zinc levels (<60 mg/dL) and one fourth had iron deficiency (haematocrit <33%) at baseline. The proportion zinc deficient was significantly lower post 12 months supplementation, in the zinc and iron folic acid group (difference in proportions -10%; 95% confidence interval -15.6% to -4.4%, p 0.0005). Only 7.7% in the zinc and iron folic acid and 7.3% in the iron folic acid group had low haematocrit. Zinc and iron folic acid supplementation had no impact on hospitalisations, overall and cause-specific. The overall death rates were similar in the two groups.

Conclusions: The lack of mortality impact may be real or the findings could have resulted from the use of lower daily zinc dosing than in morbidity prevention trials or an interaction between zinc and iron whereby adding iron, may have adversely affected potential effects of zinc on immune function and morbidity. Future research should address iron and zinc interaction effects on important functional outcomes.