title: The mechanisms for regulating absorption of Fe bis-glycine chelate and Fe-ascorbate in caco-2 cells are similar.
abstract: Inorganic iron (Fe) absorption from the diet is controlled mainly in the intestinal tract where apical Fe uptake is inversely related to the Fe content in the enterocyte. Iron bis-glycine chelate is an iron compound that may be absorbed by a mechanism different from the regulated nonheme Fe pathway. Because Fe bis-glycine chelate is used increasingly as an Fe fortificant in foods, the critical question is whether this compound is a safe Fe supplement. We compared apical Fe uptake and transepithelial transport offered either as (59)Fe bis-glycine chelate or a (59)Fe-ascorbate (Fe-AA) complex in Caco-2 cells, as a model of human intestinal epithelia, grown in different Fe concentrations in the media (0.5, 5 and 20 micro mol/L Fe). Apical Fe uptake from (59)Fe-AA and (59)Fe bis-glycine chelate did not differ nor did transepithelial transport rates. The rate of (59)Fe uptake decreased with increasing intracellular Fe concentration (P < 0.001), an indication of a common absorption regulatory mechanism. We also evaluated the effect of an excess of Fe (100 micro mol/L) provided as Fe bis-glycine chelate or Fe-AA on the incorporation of 1 micro mol/L (55)Fe-AA into Fe-replete Caco-2 cells. The inhibition of Fe bis-glycine chelate on the absorption of the extrinsic tag of (55)Fe-AA (87.5%) did not differ from that of Fe added as Fe-AA (86.8%). These results suggest that Fe derived from Fe bis-glycine chelate and Fe-AA have similar regulatory absorption mechanisms.
authors.affiliation: Micronutrients Laboratory, Institute of Nutrition and Food Technology (INTA), Santiago, Chile.
authors.forename: Dora Inés
authors.initials: DI
authors.lastname: Mazariegos
authors.forename: Fernando
authors.initials: F
authors.lastname: Pizarro
authors.forename: Manuel
authors.initials: M
authors.lastname: Olivares
authors.forename: Marco T
authors.initials: MT
authors.lastname: Nuñez
authors.forename: Miguel
authors.initials: M
authors.lastname: Arredondo
mesh_terms: D000042:Absorption; D000704:Analysis of Variance; D001205:Ascorbic Acid / Q000493:pharmacokinetics; D001682:Biological Availability; D018938:Caco-2 Cells; D002478:Cells, Cultured; D005296:Ferrous Compounds / Q000493:pharmacokinetics; D005998:Glycine / Q000031:analogs & derivatives* / Q000493:pharmacokinetics; D006801:Humans; D007501:Iron / Q000493:pharmacokinetics*; D008954:Models, Biological
chemical_list: D005296:Ferrous Compounds; C073588:bis-glycino iron II; D007501:Iron; D001205:Ascorbic Acid; D005998:Glycine