Absorption of iron in young men studied by monitoring excretion of a stable iron isotope (58Fe) in feces.

Fecal excretion of a stable iron isotope (58Fe) in five young adult men consuming a diet enriched with the isotope added as an extrinsic tag was investigated as a possible tool for the study of iron absorption. Data are presented to illustrate rapidity and completeness of unabsorbed 58Fe excretion. Procedures are outlined to investigate the extent of 58Fe re-entry into the gastrointestinal tract of the absorbed 58Fe from the label with the cumulative fecal 58Fe method and its limitations are discussed. Two methods of estimating 58Fe absorption are discussed and compared.