Biodisponibilidad de hierro en humanos / Iron bioavailability in humans

Iron (Fe) deficiency is one of principal problems of public health associated with nutrition, specially in the developing countries where the content of hem iron (Fe-Hem) of diets is very low and the Fe non hem (Fe-No Hem) has a bioavailability that usually is low, due to the fact that it is influenced by several inhibitors found in diets rich on vegetables and poor on meats. The aim of this article is to discuss aspects related to the interactions of the Fe and other compounds that modify the bioavailability of this metal, specially in the form of Fe-No Hem, in addition, some key concepts to understand the role of the liver in the regulation of the absorption of this micromineral are discussed.

La deficiencia de Fe continua siendo uno de lo principales problemas de salud pública asociados a la nutrición, especialmente en los países en vías de desarrollo donde las dietas tienen bajo contenido de Fe-Hem y alto aporte de Fe-No Hem. Este último tiene una biodisponibilidad que usualmente es baja, debido a que está afectada por los inhibidores presentes en las dietas ricas en productos de origen vegetal y pobres en carnes. El objetivo de esta revisión es discutir los aspectos relacionados con las interacciones del Fe dietario y otros compuestos que modifican la biodisponibilidad del metal, especialmente en la forma de Fe-No Hem, además, se abordan algunos conceptos claves para entender el papel del hígado en la regulación de la absorción de este micromineral.

Vesicular transport of Fe and interaction with other metal ions in polarized Caco2 Cell monolayers

Two aspects of the mechanisms by which iron is absorbed by the intestine were studied in the Caco2 cell model, using 59Fe(II)-ascorbate. Data showing the importance of vesicular processes and cycling of apotransferrin (apoTf) to uptake and overall transport of Caco2 cell monolayers (or basolateral 59Fe release) were obtained by comparing effects of: a) adding apoTf to the basal chamber; b) adding vesicular transport inhibitors; or c) cooling to 4°C. These showed that apoTf may be involved in as much as half of Fe transfer across the basolateral membrane, and that vesicular processes may also play a role in non-apoTf-dependent Fe transport. Studies were initiated to examine potential interactions of other metal ions with Fe(II) via DMT1. Kinetic data showed a single, saturable process for uptake of Fe(II) that was pH dependent and had a Km of 7 ìM. An excess of Mn(II) and Cu(I) over Fe(II) of 200: 1 (ìM: ìM) in 1 mM ascorbate markedly inhibited Fe uptake. The kinetics were not competitive. Km increased and Vmax decreased. We conclude that vesicular transport, involving endo- and exocytosis at both ends of the enterocyte, is a fundamental aspect of intestinal iron absorption and that DMT1 may function as a transporter not just for divalent but also for monovalent metal ions.

Fe(II) speciation and its uptake by free and immobilized cells of Pseudomonas fluorescens from industrial waste water.

Studies are carried out to remove Fe(II) from wastewater using free and immobilized cells of Pseudomonas fluorescens. Experiments are carried out with free cells between 6 and 8 pH and the uptake of Fe(II) is observed to be maximum at pH 7. Further experiments are done at pH 7. Studies with free and immobilized cells revealed that immobilized cells are more efficient for the removal of Fe(II) than free cells. Fe(II) uptake with Pseudomonas fluorescens is also investigated after the addition of NaCl and MgCl2 to the cells. It is found that the uptake has increased when Sodium chloride (NaCl) and Magnesium Chloride (MgCl2) mixed cells are used. Effect of deficiency of nutrients is also studied. It is found that glucose deficient conditions inhibit Fe(II) uptake more than yeast extract deficient ones. pH also plays an important role in the transport of Fe(II) across the membrane of the cells.

Utilizaçäo da água potável como veículo de nutrientes: estudos experimentais com ferro / Use of drinking water as a vehicle of nutrients: experimental studies with iron

Esta investigaçäo é parte de um projeto mayor com o objetivo de estudar a possibilidade de se usar água potável como carreador de nutrientes, tais como o ferro, para uso de comunidades. Para verificar tal possibilidade vários sais de ferro em diferentes concentraçöes foram adicionados água e analisados quanto a seus efeitos em relaçäo à cor e à turbidez. Os resultados destes estudos mostraram que o citrato férrico amoniacal foi o melhor sal no que diz respeito à manutençäo das características físicas de água potável clorada. Também foi estudada a biodisponibilidade de diversos sais de ferro adicionados a água para prevenir a anemia em ratos. Os ensaios biológicos mostraron que as formas mais adequadas de sais de ferro em água para prevenir foram: citrato férrico amoniacal, sulfato ferroso e gluconato de ferro