Erythrocyte Incorporation of Ingested 58-Iron by Infants

Abstract

ABSTRACT. The least abundant stable isotope of iron, "Fe (natural abundance 0.322 weight %), was administered orally to infants to explore the feasibility of using a stable rather than a radioisotope in studies of iron absorption. The dose of 58Fe was given between feedings at age 126 days. The mass isotope ratio, 58Fe/57Fe, was determined in blood by inductively coupled plasma mass spectroscopy and at ages ICPJMS, inductively coupled plasma mass spectrometry MIR, mass isotope ratio MR, measured ratioIron deficiency is a leading nutritional deficiency disorder among infants and children both in industrialized and developing countries (1). Although it is well recognized that development of strategies for prevention of iron deficiency requires sound knowledge of iron absorption, studies to provide this knowledge have been impeded by reluctance to administer radioisotopes to young subjects. We have recently demonstrated the feasibility of using the least abundant stable isotope of iron, "Fe (natural abundance 0.322 weight %), for studies of iron metabolism in infants and have reported data from study of four infants (2). We reported the MIR 58/57 in erythrocytes for each of four infants at 84 and 112 days of age (baseline values) and at 140, 168, and 196 days of age. A dose of "Fe was administered to each infant under standardized conditions at 126 days of age. We concluded that 58Fe was promising as a tracer for studies of iron availability in infants.We have now studied an additional five infants and, from the pooled data, have made estimates of the apparent errors of the method. We have also demonstrated for the first time in infants

The Bioavailability of Iron in Different Weaning Foods and the Enhancing Effect of a Fruit Drink Containing Ascorbic Acid

“…In adults this is generally attributed to differenccs in Fe stores (measured by serum/ plasma ferritin concentrations). (21). However, in the present study, when the relationship between Hb incorporation (all foods fed without ascorbic acid) and plasma ferritin levels was examined (23), there was no significant correlation (Spearman r = -0.212).…”

“…There are, in fact, only Individual and geometric mean (-SD, +SD) values a few isotopic studies in which Fe absorption from foods has been detcrmined in infants, either by whole body counting (16), fecal balance (17), or Hb incorporation techniques (18). In recent years, efforts have been made to develop the methodology required to use stable instead of radioisotopes, so as to enable studies to be performed directly on infants by fecal monitoring (19) or red blood cell enrichment (10,(20)(21)(22). The present report presents results of a unique study in which two stable isotopes have been administered orally to infants, and a third one was used to quantify blood enrichment with the isotopes (bioavailability) from a small volume of capillary blood using isotope dilution mass spectrometry.…”

Iron Bioavailability Studied in Infants: The Influence of Phytic Acid and Ascorbic Acid in Infant Formulas Based on Soy Isolate

“…The precision of the measurements of incorporation of stable isotopes into red blood cells can be estimated based on the uncertainties of the determination of the isotope ratios of both baseline and enriched samples (11,20). At low fractional Fe incorporation, when the measured isotope ratios are close to the detection limit, the errors increase.…”

“…The quantity of administered 5 8~e and 5 7~e incorporated into red blood cells was calculated in a manner similar to that used by Fomon et al (20). Circulating Fe was calculated based on body weight and on the assumption of 65 mL/kg body weight (20). Furthermore, 90% of initially absorbed Fe was assumed to be incorporated into red blood cells (12)-…”

Preparation and Bioavailability Analysis of Ferrous Bis Alanine Chelate as a New Micronutrient for Treatment of Iron Deficiency Anemia

“…Studies have suggested that hemoglobin level is a valid parameter to evaluate whether the new iron formulations have improved absorption and bioavailability. 23 Higher level of mean hemoglobin concentration in group IV and group III demonstrates that iron chelate can be considered as a preferred formulation to increase the gastrointestinal absorption and bioavailability of iron. One aspect of this impressive absorption of iron is the neutralization of this ion during the chelating process which can prevent the iron interactions with phenolic compounds.…”