Comparison of ingestive effects of brewer's yeast,casein, and soy protein on bioavailability of dietary iron

The effects of brewer's yeast, casein, and soy protein intakes on the absorption and retention as well as the incorporation into hemoglobin and systemic iron stores of dietary iron were examined in an animal experiment with growing rats. Relative biological values (RBV) of iron in the rats fed casein (C), soy protein (SP), and yeast (Y) diets were 1.00, 0.31, and 1.77, respectively. The apparent absorption of iron in Y-diet-fed rats was significantly higher than that in C- or SP-diet-fed rats. The hemoglobin regeneration efficiency (HRE) of iron in Y group was significantly higher than those in C and SP groups. As a result of search for iron-absorptive enhancers (IAE) in yeast, RBV and HRE of the yeast-cell-wall-including diet turned out to be significantly higher than those of its lacking diet. These results suggest that IAE occurring in the yeast cell wall may be effective for iron absorption.