Comparison of changes in the uptake and mucosal processing of iron in riboflavin-deficient rats.

Riboflavin deficiency in rats resulted in a reduction in the transfer of 59Fe from an intragastric dose to plasma compared to age-matched or weight-matched controls. The uptake of iron by brush-border membrane vesicles made from intestinal mucosa of riboflavin-deficient rats was much less than identically-prepared vesicles from control groups. Although the mucosal content of 59Fe was smaller in riboflavin-deficient rats thirty minutes after dosing, the relative distribution of 59Fe between the mucosal iron-binding proteins, ferritin and transferrin, was not changed compared to the control groups. These studies suggest that the impairment in iron absorption in riboflavin deficiency is primarily the result of a reduced uptake of iron into the mucosal cell and not a redistribution of iron between iron-binding proteins inside the mucosal cell.