Abstract
Interference with zinc absorption is a proposed explanation for adverse effects of supplemental iron in iron-replete children in malaria endemic settings. We examined the effects of iron in micronutrient powder (MNP) on zinc absorption after three months of home fortification with MNP in maize-based diets in rural Kenyan infants. In a double blind design, six-month-old, non-anemic infants were randomized to MNP containing 5 mg zinc, with or without 12.5 mg of iron (MNP + Fe and MNP − Fe, respectively); a control (C) group received placebo powder. After three months, duplicate diet collections and zinc stable isotopes were used to measure intake from MNP + non-breast milk foods and fractional absorption of zinc (FAZ) by dual isotope ratio method; total absorbed zinc (TAZ, mg/day) was calculated from intake × FAZ. Mean (SEM) TAZ was not different between MNP + Fe (n = 10) and MNP − Fe (n = 9) groups: 0.85 (0.22) and 0.72 (0.19), respectively, but both were higher than C (n = 9): 0.24 (0.03) (p = 0.04). Iron in MNP did not significantly alter zinc absorption, but despite intakes over double estimated dietary requirement, both MNP groups’ mean TAZ barely approximated the physiologic requirement for age. Impaired zinc absorption may dictate need for higher zinc doses in vulnerable populations.
Highlights
IntroductionOral iron supplementation has been associated with increased mortality and rates of adverse events from infectious diseases in older iron-replete infants and toddlers in a malaria endemic area [1]
Iron deficiency and iron deficiency anemia are among the most prevalent and intractable public health problems in infants and young children, in malaria-endemic, resource-limited settings.oral iron supplementation has been associated with increased mortality and rates of adverse events from infectious diseases in older iron-replete infants and toddlers in a malaria endemic area [1].These adverse outcomes have prompted critical re-evaluation of approaches to prevent iron deficiency and iron deficiency anemia [2,3]
We examined in a vulnerable population the effects on zinc absorption of increased iron intake by comparing micronutrient powder (MNP) with and without iron, compared to a study group receiving placebo MNP as a control
Summary
Oral iron supplementation has been associated with increased mortality and rates of adverse events from infectious diseases in older iron-replete infants and toddlers in a malaria endemic area [1]. These adverse outcomes have prompted critical re-evaluation of approaches to prevent iron deficiency and iron deficiency anemia [2,3]. Interference with zinc absorption and/or metabolism is one proposed explanation for the adverse effects of iron supplements in iron replete subjects in malaria endemic areas [2]. In two studies of lactating women, iron supplementation was associated with lower fractional absorption of zinc [9,10]
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