Dose-response trial of prophylactic zinc supplements, with or without copper, in young Ecuadorian children at risk of zinc deficiency.
What this study found
Daily zinc supplementation improved zinc status and reduced diarrhea, with the clearest benefit seen at 3 mg/d and 7 mg/d. Mean plasma zinc increased progressively with higher zinc doses (P 0.001), and diarrhea incidence was 21-42% lower in children receiving any zinc dose than in placebo (P 0.01 overall); the reductions were significant for 3 mg Zn/d (P 0.04) and 7 mg Zn/d (P 0.01). There were no significant differences in other morbidity symptoms or in growth across groups. Ten mg/d zinc did not produce adverse effects on copper or iron status or on lipoprotein concentrations, and adding…
- Study & population
- Dose-response trial in Ecuadorian children 12 to 36 months old who were at risk of zinc deficiency and had low length-for-age.
- Intervention
- Children received oral zinc sulfate syrup for 6 months in one of three daily doses: 3 mg, 7 mg, or 10 mg zinc.
- Key limitation
- The intervention lasted 6 months and enrolled a specific population of young Ecuadorian children with low length-for-age, which limits generalizability.
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Open PDFOriginal abstract
BACKGROUND Multiple studies have shown the benefits of zinc supplementation among young children in high-risk populations. However, the optimal dose and safe upper level of zinc have not been determined. OBJECTIVES The objectives of this study were to measure the effects of different doses of supplemental zinc on the plasma zinc concentration, morbidity, and growth of young children; to detect any adverse effects of 10 mg supplemental Zn on markers of copper or iron status; and to determine whether any adverse effects are alleviated by providing copper with zinc. DESIGN This randomized, double-masked, community-based intervention trial was conducted in 631 Ecuadorian children who were 12-30 mo old at baseline and who had initial length-for-age z scores <-1.3. Children received 1 of 5 daily supplements for 6 mo: 3, 7, or 10 mg Zn as zinc sulfate, 10 mg Zn + 0.5 mg Cu as copper sulfate, or placebo. RESULTS The change in plasma zinc concentration from baseline was positively related to the zinc dose (P < 0.001). Zinc supplementation, including doses as low as 3 mg/d, reduced the incidence of diarrhea by 21-42% (P < 0.01). There were no other significant group-wise differences. CONCLUSIONS Zinc supplementation with a dose as low as 3 mg/d increased plasma zinc concentrations and reduced diarrhea incidence in the study population. There were no observed adverse effects of 10 mg Zn/d on indicators of copper or iron status. The current tolerable upper level of zinc recommended by the Institute of Medicine should be reassessed for young children.