Bioavailability of Fe, Ca, P and Mg in Fe-deficient rats treated with different sources of dietary iron

Iron deficiency (DO) markedly decreases the concentration of iron and calcium in the liver, femur and sternum. We investigated the effect of the source of dietary iron [ferric citrate alone (citrate diet), or combined with bovine blood at a proportion of 1:1 (citrate+heme diet), and ferric protein (protein-Fe diet)] on the nutritive utilization of Fe, Ca, P and Mg in anemic and healthy rats. All diets contained the same amount of Fe (40 mg/kg diet). In Fe-deficient rats (DT) fed citrate, citrate+heme or protein-Fe diet the apparent digestibility coefficient (ADC) of Fe were 39 %, 37% and 94% greater than in the respective control groups (C); hemoglobin regeneration efficiencies (HRE) were respectively 47%, 51%, and 172% greater than in the control groups. The ADC of Ca was not affected by Fe deficiency, whereas the ADC of Mg decreased significantly, and that of P increased under our experimental conditions. In Fe-deficient rats fed Fe for 10 days (DT), the concentrations of hemoglobin approached normal values. However, serum Fe remained low, indicating that Fe reserves were still depleted. Hepatic and femoral Fe concentrations were also lower in all DT groups, whereas Fe concentrations in the sternum increased significantly, suggesting an increase in erythropoiesis. After supply of dietary Fe for 10 days in iron-deficient groups (DT), Ca and P concentrations increased in sternum, a site assumed to have higher requirements for these minerals. In the liver these values tended to normalize, whereas in the femur Ca and P stores remained depleted. Mg concentrations after the replenishment period generally approached normality in all three organs.