THE INFLUENCE OF DIFFERENT PROTEIN-SOURCES ON PHYTATE INHIBITION OF NONHEME-IRON ABSORPTION IN HUMANS

The inhibiting effect of phytate on nonhemeiron absorption from differ ent protein sources was examined in human subjects using extrinsic rad ioiron labeling. A drink containing maltodextrose and corn oil was use d as a control meal to which was added sufficient sodium phytate to pr ovide 300 mg phytic acid and/or various protein sources. The proteins were selected to cover a broad range of effects on bioavailability and included egg white, meat, and phytate-free soy protein. When sodium p hytate alone was added, there was a pronounced 83-90% reduction in mea n absorption in separate studies with a composite average decline of 8 6%. Despite a wide range in absorption from meals containing the three protein sources, a remarkably similar relative inhibition was observe d when sodium phytate was added. No significant difference in the inhi biting effect of phytate could be detected with additions ranging from the equivalent of 50-300 mg phytic acid to a meal containing egg whit e as the protein source. Our studies found no evidence that the inhibi ting effect of phytate depends on the protein composition of the meal.