Effect of stabilising amino acids on the digestive absorption of heme and non-heme iron

We used the Ussing chamber model to study heme iron absorption by rat duode nal mucose. Heme iron was obtained by enzymic digestion of bovine haemoglob in and concentration of heme (HPH). Its uptake and mucosal transfer was com pared to iron gluconate (Gluc), at 100 mu M and 1 mM. At 100 mu M iron upta ke (Qtot), mucosal retention (Qm) and transfer across the mucosa (Qs) was s imilar for the two sources of iron. Qs was significantly higher at 1 mM for Gluc but not for HPH, and was associated with higher levels of Qm. Additio n of L-histidine did not improve iron absorption and indeed it decreased it if iron was provided as Gluc. L-cysteine increased the transfer of iron of both sources. In the in vitro model using rat digestive mucosa, heme iron appeared to be an efficiently used source of iron, which might prevent its accumulation by gut when supplied in excess. (C) Inra/Elsevier, Paris.