Iron absorption by humans and swine from Fe(III)-EDTA. Further studies.

Studies on iron absorption from Na59Fe-EDTA in humans have shown that only a small proportion of the iron absorbed is excreted by the kidney, less than 1% of the dose administered. The pathway of Na55Fe-[2-14C]EDTA absorption and excretion when administered orally was studied in swine. A certain proportion (about 5%) of the 55Fe is split from the EDTA complex in the lumen of the gut, absorbed mainly from the pylorus and upper jejunum, transferred to plasma transferrin and then incorporated into the circulating hemoglobin. A small proportion of the iron absorbed, less than 1% of the dose administered, is excreted by the kidney, to a degree similar to that excreted by humans. The rest of the iron is eliminated in the feces, about 3% in a soluble form possibly still bound to EDTA and the greater part, about 92%, in an insoluble form. About 5% of the 14C is absorbed almost uniformly along the pyloric duodenal and jejunal mucosa, then transferred slowly to the plasma and excreted by the kidney within 48 hours. The rest of the 14C was excreted in the feces, about 80% in a soluble form and 20% in the insoluble fraction.