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United States Department of Agriculture

Agricultural Research Service

Research Project: ABSORPTION AND METABOLISM OF ESSENTIAL MINERAL NUTRIENTS IN CHILDREN

Location: Children's Nutrition Research Center

Title: Iron supplementation does not affect copper and zinc absorption in breastfed infants

Authors
item Domellof, Magnus -
item Hernell, Olle -
item Abrams, Steven -
item Chen, Zhensheng -
item Lonnerdal, Bo -

Submitted to: American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 6, 2008
Publication Date: January 15, 2009
Citation: Domellof, M., Hernell, O., Abrams, S.A., Chen, Z., Lonnerdal, B. 2009. Iron supplementation does not affect copper and zinc absorption in breastfed infants. American Journal of Clinical Nutrition. 89(1):185-190.

Interpretive Summary: Iron supplements are commonly recommended for infants, but may hurt a child's ability to absorb zinc and copper. The goal of this study was to determine the potential effects of iron supplementation on zinc and copper absorption in infants at 6 and 9 months of age. Twenty-five healthy breastfed term infants were studied. Six received a small iron supplement from 4 to 9 months, 8 were supplemented from 6 to 9 months, and 11 received placebo only. Zinc and copper absorption was measured at 6 and 9 months of age, using stable (non-radioactive) isotopes. No significant difference was observed in zinc or copper absorption between 6 and 9 months of age, nor was any significant effect of prior iron supplementation observed on zinc or copper absorption. We concluded that our study does not support the contention that iron supplements hurt the absorption of zinc or copper in healthy breastfed infants from 6 to 9 months of age.

Technical Abstract: Iron supplements are commonly recommended for infants but were suggested to inhibit zinc and copper absorption. The objective of this study was to investigate potential effects of iron supplementation, infant age, and mineral status on zinc and copper absorption in infants at 6 and 9 mo of age. Twenty-five healthy breastfed term infants were recruited from a larger randomized iron supplementation trial. Six of these infants received iron supplements (1 mg · kg–1 · d–1) from 4 to 9 mo, 8 were supplemented from 6 to 9 mo, and 11 received placebo only. Zinc and copper absorption was measured at 6 and 9 mo of age, using orally administered 70Zn and 65Cu and fecal monitoring of recovered stable isotopes. Mean (+/- SD) zinc absorption was 51.9 +/- 17.9%, and mean copper absorption was 79.0 +/- 13.5%. No significant difference was observed in zinc or copper absorption between 6 and 9 mo of age. When combining all measurements, no significant effect of prior iron supplementation was observed on zinc or copper absorption. No significant correlation was observed between plasma zinc and zinc absorption or between plasma copper and copper absorption. No significant correlation was observed between erythrocyte copper-zinc–dependent superoxide dismutase activity and copper absorption. The study does not support the contention that iron supplements inhibit the absorption of zinc or copper in healthy breastfed infants at 6–9 mo of age. In addition, we did not find any age-related changes in zinc or copper absorption between 6 and 9 mo of age.

Last Modified: 9/29/2014