Bioavailability to anemic rats of iron from fresh, cooked or nitrosylated hemoglobin and myoglobin

Bioavailabilities of heme iron prepared from lyophilized, fresh, cooked, nitrosylated hemoglobin and purified myoglobin in semipurified diets were investigated in two experiments. In experiment 1, the bioavailabilities of porcine and bovine hemoglobins were about one-third that for ferrous sulfate regardless of hemoglobin treatments. The efficiency of hemoglobin regeneration by anemic rats fed nitrosylated pork hemoglobin was significantly depressed compared with that by those fed unnitrosylated products. Cooking did not affect the availability of the heme iron, whereas washing tended to increase it. In experiment 2, the hemoglobin regeneration efficiency of the purified myoglobin diet was lower than reported by others for meat diets, and was even lower than that of the purified hemoglobin diet. The respective efficiency values for the basal, basal + FeSO4, hemoglobin, and myoglobin diets (experiment 2) were 0.073, 0.581, 0.199, and 0.125. The efficiencies of converting hemoglobin and ferrous sulfate iron into hemoglobin by the anemic rats were very similar to reported absorption values for these iron sources by iron-deficient human subjects.