Zinc Absorption from Micronutrient Powder Is Low but Is not Affected by Iron in Kenyan Infants

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.

Mode of oral iron administration and the amount of iron habitually consumed do not affect iron absorption, systemic iron utilisation or zinc absorption in iron-sufficient infants: a randomised trial

“…The results of our study support the limited research that shows no evidence that consumption of foods fortified with Fe has a negative effect on Zn absorption (30,32) or Zn status (32,33) in young children. The absorption of Zn from the study formulae was similar to that previously reported in infants (36) .…”

“…Whether Fe supplements given alone compromise infant Zn nutrition is still unclear (21,(27)(28)(29) . When present as a fortificant, Fe does not appear to inhibit Zn absorption (30)(31)(32) , impair Zn status (32)(33)(34) or result in measurable circulating non-transferrin-bound Fe (16) . Few studies, however, have addressed this in infants.…”

Zinc Absorption Is Not Related to Dietary Phytate Intake in Infants and Young Children Based on Modeling Combined Data from Multiple Studies

“…The data originated from studies of zinc absorption in 262 infants and children conducted in poor, rural communities mostly in economically developing countries (China, India, Kenya, Malawi, and Zambia) (10)(11)(12)(13)(14)(15)(16) and in a westernized, resource-adequate community in the United States (17) ( Table 1). The subjects were apparently healthy, with no chronic illnesses or conditions affecting zinc absorption.…”

“…For example, biomarkers specific to intestinal inflammation would be of particular interest in addition to CRP, which reflects systemic inflammation. The highly prevalent condition of environmental enteropathy has been proposed to have a negative impact on zinc absorption (11,38,39). From the coefficients of determination of the statistical models it was apparent that the models generally accounted for no more than 50-60% of the variance of TAZ, which is typical of modeling of individual data from stable-isotope studies of human nutrition.…”

Neurodevelopment: The Impact of Nutrition and Inflammation During Infancy in Low-Resource Settings

“…Although a similar "master regulator" analogous to hepcidin has not been identified for other micronutrients, data are emerging to suggest adverse effects of environmental enteric dysfunction and inflammation on zinc absorption and homeostasis. 13,46,47 Another mechanism by which disrupted gut health may impact development is through alterations in the gut microbiota which, through interaction with the developing innate immune system, can drive elevations in proinflammatory and antiinflammatory cytokines and influence brain function. 48 Such early and enduring inflammatory stimuli have also been linked to a risk of systemic metabolic disease associated with later noncommunicable diseases, particularly in settings where access to more abundant caloric intake is emerging.…”