RESUMEN
Iron is an essential element for human life and its nutritional status in the human body is directly linked to human health. More than 1015 atoms of iron per second are necessary for the maintenance of haemoglobin formation. To predict iron bioavailability three approaches are normally employed: (a) faecal recovery; (b) plasma appearance; and (c) erythrocyte incorporation (the most used). Isotope Pattern Deconvolution (IPD) is a mathematical tool that allows the isolation of distinct isotope signatures from mixtures of natural abundance and enriched tracers. In this work we propose a novel strategy to assess erythrocyte iron incorporation, based on the use of an iron stable isotope (57Fe) and the IPD concept. This strategy allows direct calculation of the exogenous concentration of 57Fe incorporated into RBCs after supplementation. In this way, to determine the mass of iron incorporated into erythrocytes, the unique prediction that must be made is the blood volume, estimate to reproduce the natural dilution of the tracer (57Fe) in the blood. This novel bioanalytical approach was applied for the measurements of iron incorporation and further iron absorption studies in humans, using a group of twelve healthy participants, that should be further evaluated for the assessment of other chemical elements that could be of health concerns and directly impact society.
Asunto(s)
Eritrocitos , Hierro , Humanos , Hierro/metabolismo , Isótopos de Hierro/metabolismo , Eritrocitos/metabolismo , Plasma , Disponibilidad BiológicaRESUMEN
BACKGROUND: Fortification of milk formulas with iron is a strategy widely used, but the absorption of non-heme iron is low. The purpose of this study was to measure the bioavailability of two iron fortified milk formulas designed to cover toddlers´ nutritional needs. These milks were fortified with iron sulfate stabilized with maltodextrin and citric acid. METHODS: 15 women (33-47 years old) participated in study. They received on different days, after an overnight fast, 200 mL of Formula A; 200 mL of Formula B; 30 mL of a solution of iron and ascorbic acid as reference dose and 200 mL of full fat cow's milk fortified with iron as ferrous sulfate. Milk formulas and reference dose were labeled with radioisotopes (59)Fe or (55)Fe, and the absorption of iron measured by erythrocyte incorporation of radioactive Fe. RESULTS: The geometric mean iron absorption corrected to 40% of the reference dose was 20.6% for Formula A and 20.7% for Formula B, versus 7.5% of iron fortified cow's milk (p < 0.001). The post hoc Sheffé indeed differences between the milk formulas and the cow's milk (p < 0.001). CONCLUSION: Formulas A and B contain highly bioavailable iron, which contributes to covering toddlers´ requirements of this micronutrient.