Effect of histidine, cysteine, glutathione or beef on iron absorption in humans.

One hundred thirteen subjects participated in iron absorption studies in which histidine, cysteine, reduced glutathione or beef were administered with test meals. Increasing doses of histidine from 416 to 2080 mg did not affect the absorption of 2 mg of corn iron. Reduced glutathione significantly increased the absorption from nonheme and heme iron present in black beans, corn and hemoglobin. Increasing doses of either cysteine or glutathione produce the same trend in the increase of absorption from corn iron as that observed from beef. The results suggest that the effect of cysteine on iron absorption is similar in the peptide form and as a single molecule.