Absorption of iron from ferric hydroxide polymers introduced into ligated rat duodenal segments

The availability of iron from 59Fe-labeled polymeric ferric hydroxides and low-molecular-weight ferric complexes (LMW iron) was compared by using ligated rat duodenal segments, in vivo. The effect of iron status was assessed by using iron-adequate (Hb 12.3-15.5 g/dl) and iron-deficient (Hb 8.1-10.6 g/dl) rats for each iron treatment. Analysis of data from the animal experiment showed: less (P less than 0.01) iron from polymers [6.8% (iron adequate) and 7.7% (iron deficient)] was transferred to the carcass than from LMW iron [29.2% (iron adequate) and 47.9% (iron deficient)] and iron-deficient animals absorbed more iron than iron-adequate rats from LMW iron but not from polymeric iron. Solubility studies showed that these data could not be attributed to solubility differences between polymers and LMW iron. The results of this experiment suggest that in the intestine factors or conditions that depolymerize iron or prevent polymer formation could enhance iron absorption.