In developing countries the duration and severity of diarrheal illnesses are greatest among infants and young children with malnutrition and impaired immune status, both factors that may be associated with zinc deficiency. In children with severe zinc deficiency, diarrhea is common and responds quickly to zinc supplementation. To evaluate the effects of daily supplementation with 20 mg of elemental zinc on the duration and severity of acute diarrhea, we conducted a double-blind, randomized, controlled trial involving 937 children, 6 to 35 months of age, in New Delhi, India. All the children also received oral rehydration therapy and vitamin supplements. Among the children who received zinc supplementation, there was a 23 percent reduction (95 percent confidence interval, 12 percent to 32 percent) in the risk of continued diarrhea. Estimates of the likelihood of recovery according to the day of zinc supplementation revealed a reduction of 7 percent (95 percent confidence interval, -9 percent to +22 percent) in the risk of continued diarrhea during days 1 through 3 and a reduction of 38 percent (95 percent confidence interval, 27 percent to 48 percent) after day 3. When zinc supplementation was initiated within three days of the onset of diarrhea, there was a 39 percent reduction (95 percent confidence interval, 7 percent to 61 percent) in the proportion of episodes lasting more than seven days. In the zinc-supplementation group there was a decrease of 39 percent (95 percent confidence interval, 6 percent to 70 percent) in the mean number of watery stools per day (P = 0.02) and a decrease of 21 percent (95 percent confidence interval, 10 percent to 31 percent) in the number of days with watery diarrhea. The reductions in the duration and severity of diarrhea were greater in children with stunted growth than in those with normal growth. For infants and young children with acute diarrhea, zinc supplementation results in clinically important reductions in the duration and severity of diarrhea. Among children in developing countries, diarrheal illnesses, especially those of prolonged duration, are important causes of growth retardation and death.1–5 Episodes of diarrhea, which usually resolve within a few days in a healthy child, persist longer in children with malnutrition,6,7 impaired cellular immunity,7–9 or recurrent diarrhea.10 We hypothesized that zinc deficiency is a link between these risk factors and the duration of diarrhea. Diarrhea is consistently found in children with severe zinc deficiency,11,12 as well as in animals with zinc depletion13; it responds quickly to zinc supplementation.14 Zinc deficiency can result in growth retardation, especially.
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