A community-based randomized controlled trial of iron and zinc supplementation in Indonesian infants: interactions between iron and zinc.
What this study found
Daily supplementation improved micronutrient status, but the combined iron-plus-zinc regimen was less effective than single-nutrient supplementation. At 12 months, hemoglobin differed across groups (Fe 119.4 ± 15.3 g/L; Zn 115.7 ± 15.2; Fe+Zn 115.3 ± 13.9; placebo 113.5 ± 16.0; P=0.012), ferritin was highest with iron alone (46.5 ± 2.0 g/L; P<0.001), and serum zinc was highest with zinc alone (11.58 ± 1.41 mol/L; P<0.001). Two-factor ANOVA showed significant iron-zinc interaction for hemoglobin (P=0.021) and serum ferritin (P=0.032), consistent with iron reducing zinc effectiveness in the…
- Study & population
- Community-based randomized controlled trial in healthy singleton infants in Central Java, Indonesia, enrolled at about 6 months of age and followed to 12 months.
- Intervention
- Children received daily oral syrup from 6 to 12 months of age.
- Key limitation
- Arm sizes were modest and follow-up lasted only 6 months, limiting precision and long-term inference.
View source
Open PDFOriginal abstract
BACKGROUND Combined supplementation with iron and zinc during infancy may be effective in preventing deficiencies of these micronutrients, but knowledge of their potential interactions when given together is insufficient. OBJECTIVE The goal was to compare the effect in infants of combined supplementation with iron and zinc and of supplementation with single micronutrients on iron and zinc status. DESIGN Indonesian infants (n = 680) were randomly assigned to daily supplementation with 10 mg Fe (Fe group), 10 mg Zn (Zn group), 10 mg Fe + 10 mg Zn (Fe+Zn group), or placebo from 6 to 12 mo of age. Venous blood samples were collected at the start and end of the study. Five hundred forty-nine infants completed the supplementation and had both baseline and follow-up blood samples available for analysis. RESULTS Baseline prevalences of anemia, iron deficiency anemia (anemia and low serum ferritin), and low serum zinc (< 10.7 micromol/L) were 41%, 8%, and 78%, respectively. After supplementation, the Fe group had higher hemoglobin (119.4 compared with 115.3 g/L; P < 0.05) and serum ferritin (46.5 compared with 32.3 microg/L; P < 0.05) values than did the Fe+Zn group, indicating an effect of zinc on iron absorption. The Zn group had higher serum zinc (11.58 compared with 9.06 micromol/L; P < 0.05) than did the placebo group. There was a dose effect on serum ferritin in the Fe and Fe+Zn groups, but at different levels. There was a significant dose effect on serum zinc in the Zn group, whereas no dose effect was found in the Fe+Zn group beyond 7 mg Zn/d. CONCLUSION Supplementation with iron and zinc was less efficacious than were single supplements in improving iron and zinc status, with evidence of an interaction between iron and zinc when the combined supplement was given.