INCLEN Childnet Zinc Effectiveness for Diarrhea (IC-ZED) Group (2006) Zinc supplementation in acute diarrhea is acceptable, does not interfere with oral rehydration, and reduces the use of other medications: a randomized trial in five countries. J Pediatr Gastroenterol Nutr 42: 300–305

Zinc supplementation is known to reduce the duration of diarrhea and decrease the requirement for antibiotics and other medication. There is concern, however, that in developing countries zinc supplementation might reduce use of oral rehydration solution (ORS), which is vital for the prevention of childhood death from diarrhea. The INCLEN study, therefore, aimed to evaluate the effects of zinc supplementation on medication use, and particularly on ORS use, in five developing countries.

In the study, 2,002 children between the ages of 2 and 59 months with acute diarrhea were randomly allocated to receive either ORS and 20 mg zinc orally each day or ORS alone. Outcomes included patient compliance with zinc supplementation, ORS use in the 24 h before first follow-up, and use of other medication. The team also provided counseling and culturally appropriate messages to parents of children given zinc, to encourage use of the supplement.

In all but one of the sites, use of ORS was the same between the two groups on days 3 to 5. Less medication was used by children who were given zinc (absolute difference 3.8%, 95% CI 1.7–5.9%) and compliance with zinc supplementation was 83.8% (95% CI 81–86%). The rate of vomiting (a possible side effect of zinc) did not differ between groups.

In conclusion, the use of zinc alongside culturally appropriate messages does not affect ORS use in acute diarrhea but does reduce the requirement for other medications.