The enhancement of nonheme iron bioavailability by beef protein in the rat.

Beef protein was found to enhance the bioavailability of nonheme iron in the rat. Anemic rats were fed diets containing soy protein concentrate or rice bran as the source of nonheme iron with either lactalbumin or distilled water-washed beef, which was heme free. The criteria used to determine the relative biological value (RBV) of iron was the difference between the products of final hemoglobin x final weight and initial hemoglobin x initial weight during the repletion period. Animals fed diets with only lactalbumin as a source of dietary protein and graded levels of FeSO4 (RBV of FeSO4 = 100%) served as controls. The RBV of the endogenous iron in soy protein and rice bran was found to be 91 and 46%, respectively. Substituting washed beef for lactalbumin increased the RBV of soy protein iron to 96% (results not statistically significant) and of rice bran iron to 75% (results significant, P less than or equal to 0.05). These findings demonstrate the "meat factor" effect in the rat for the first time. Two days after completion of the 11-d hemoglobin regeneration period, the apparent absorption of iron was measured during a 60-h balance period. The apparent absorption of iron by rats fed diets containing beef tended to be higher, compared to animals fed diets containing lactalbumin.