Long-term consumption of beef extended with soy protein by children, women and men: III. Iron absorption by adult men.

Forty-nine ostensibly healthy men consumed either patties of all-beef or beef extended with soy-isolate, -concentrate or -flour as the principal protein source in 1 to 2 meals daily for 180 days. Iron status was monitored by absorption of radioiron from a reference dose of ferrous ascorbate and by serum ferritin concentration. In addition, nonheme iron absorption from a test meal of the respective beef pattie consumed for the 180 days was estimated by the extrinsic tag procedure. There was no detrimental effect on iron stores as indexed by reference ferrous ascorbate absorption or serum ferritin concentration. Absorption of nonheme iron from the test meals was low except for individuals having indices of low iron stores. When adjusted for the effect of level of iron stores the relative absorption of nonheme iron from soy-isolate and -flour containing meals was greater than from the all-beef meal, indicating marked differences in the effect on iron absorption by different soy products. Consumption of soy-extended beef should have no detrimental effect on iron status of adult men if consumed in mixed diets at the level used in this study.