Mucosal uptake, mucosal transfer and retention of a therapeutic dose of iron.

The absorption of a pharmacological dose of iron was assessed by determination of mucosal uptake, mucosal transfer and retention of 33 mg (Fe(II) as ferrous sulphate and ferrous ascorbate. 20 subjects were studed in a cross-over trial, 11 with normal iron stores and 9 with iron deficiency according to the serum ferritin concentrations. The activity of 59Fe and 51Cr (administered as a non-absorbable indicator) was measured by whole-body counting. There was no difference in absorption between the two iron compounds in normal subjects. Absorption of ferrous ascorbate averaged 52% higher than ferrous sulphate in subjects with iron deficiency. The difference was the result of higher mucosal uptake, probably because oxidation of Fe(II) in the alkaline milieu of the intestine, which leads to formation of non-absorbable Fe(III) complexes, was prevented. The mucosal transfer fraction of both compounds was identical.