Universidad de Córdoba BIODISPONIBILIDAD MINERAL DE ...

Resultados
iron bioavailability is much smaller than heme iron and it depends on several
dietary and physiologic factors. As a consequence of this, we can think that
heme and non-heme iron are absorbed by two totally different pathways; the
first one, i.e. heme group, enters intact in the mucous cell and once inside the
cell, it is separated from protoporphyrin by the action of hemooxigenase
(Carpenter & Mahoney, 1992). Nevertheless, the mechanism by which nonheme
iron is captured and transported through intestinal mucous as well as its
controlling regulatory mechanism, remain without clarifying (Benito & Miller,
1998).
Due to physiological factors are hardly controlled, an extensive study of
dietetic factors should be taken into account. The aim of this paper is to
accurately review all the investigations reported in the last decade related to
dietetic factors which influence the bioavailability of different iron forms.
Heme-iron availability
Heme iron is absorbed by mucus intestinal cells as an intact
metaloporphyrin after having been separated from globin by several digestive
enzymes (Grasbeck et al, 1982). It seems that this porphyrin ring is responsible
for the high absorption of heme iron in comparison to nonheme iron (South et
al, 2000). However, other authors (Fly & Czarnecki-Maulden, 2000) attribute
this effect to the protein portion of hemoglobin molecule since it is possible that
peptides from globin digestion may improve iron bioavailability through an
increase on its solubility. Once inside enterocite, iron is liberated from porphyrin
135