COMPARISON OF BIOAVAILABILITY AND HEMOGLOBIN REPLETION OF FERRIC AND FERROUS IRON INFUSED INTO THE CECUM IN ANEMIC RATS

The bioavailability of ferrous and ferric iron following cecal infusion was compared by assessing the hemoglobin regeneration method in ileally fistulated anemic rats. Rats were fed an iron-deficient diet (8 mg Fe/kg diet) for 14 days after recovery from surgery. The anemic rats were then divided into three groups of 11 rats. Group 1 (control) was fed an iron-adequate diet (45 mg Fe/kg diet) and infused with NaCl solution (150 mM). Group 2 and 3 were fed an iron-deficient diet and infused with ferrous sulfate [Fe(II)] suspension or ferric sulfate [Fe(III)] solution (800 ppm as Fe, pH 6.8) to provide the same amount of iron as that consumed one day before by the control group. NaCl, Fe(II) and Fe(III) were infused through the fistula as two times (1000h and 1800h) for 14 days. The volume of NaCl infused was about equal to the volume of Fe(II) suspension and Fe(III) solution infused. Hemoglobin regeneration efficiency, hematocrit, plasma iron concentration, transferrin saturation, total iron-binding capacity, iron contents in organs (liver, spleen and kidney), body weight gain and food intake were almost the same among groups. These results suggest that inorganic iron is absorbed from the large intestine and is not influenced by forms of iron, ferrous iron or ferric iron.