title: The effect of calcium on non-heme iron uptake, efflux, and transport in intestinal-like epithelial cells (Caco-2 cells).
abstract: It has been suggested that calcium inhibits the absorption of dietary iron by directly affecting enterocytes. However, it is not clear if this effect is due to a decreased uptake of iron or its efflux from enterocytes. We studied the effect of calcium on the uptake, efflux, and net absorption of non-heme iron using the intestinal-like epithelial cell line Caco-2 as an in vitro model. Caco-2 cells were incubated for 60 min in a buffer supplemented with non-heme iron (as sulfate) and calcium to achieve calcium to iron molar ratios ranging from 50:1 to 1,000:1. The uptake, efflux, and net absorption of non-heme iron were calculated by following a radioisotope tracer of (55)Fe that had been added to the buffer. Administration of calcium and iron at molar ratios between 500 and 1,000:1 increased the uptake of non-heme iron and decreased efflux. Calcium did not have an effect on the net absorption of non-heme iron. At typical supplementary doses for calcium and non-heme iron, calcium may not have an effect on the absorption of non-heme iron. The effect of higher calcium to iron molar ratios on the efflux of non-heme iron may be large enough to explain results from human studies.
authors.affiliation: Laboratorio de Micronutrientes, Instituto de Nutrición y Tecnología de los Alimentos (INTA), Universidad de Chile, Santiago, Chile. dgaitan@inta.cl
authors.forename: Diego Alejandro
authors.initials: DA
authors.lastname: Gaitán
authors.forename: Sebastian
authors.initials: S
authors.lastname: Flores
authors.forename: Fernando
authors.initials: F
authors.lastname: Pizarro
authors.forename: Manuel
authors.initials: M
authors.lastname: Olivares
authors.forename: Miriam
authors.initials: M
authors.lastname: Suazo
authors.forename: Miguel
authors.initials: M
authors.lastname: Arredondo
mesh_terms: D001692:Biological Transport; D018938:Caco-2 Cells; D002118:Calcium / Q000008:administration & dosage / Q000494:pharmacology*; D006801:Humans; D007413:Intestinal Mucosa / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*
chemical_list: D007501:Iron; D002118:Calcium