Abstract
The ihhibitory effect of phytic acid (inositol hexakisphosphate: IP6) on mineral availability is widely known. However, the effects of inositol phosphates (IPn), which are intermediate products of phytate hydrolysis, are not clear. We have prepared IPn by enzymatic dephosphorylation of sodium phytate, and effects of inositol tetrakisphosphate (IP4), inositol trisphosphate (IP3) and inositol bisphophate (IP2) on Ca, Mg and Zn availability were investigated as compared with an inorganic phosphorus compound (Na2HPO4) and IP6 in growing rats for 4 weeks. Phosphorus from IP2-4 was available as well as Na2HPO4 and their apparent absorptions of P were higher than that of IP6. There was no difference in Ca absorption and retention among the experimental diets. Compared with IP6, increased Mg and Zn absorption from diet containing IPn with fewer phosphorus groups was observed, and Mg retention with the IP2 diet was even higher than with the Na2HPO4-containing diet. Our data suggest that inositol phosphates are a good dietary phosphorus source, and that inositol bisphosphate may have a significant effect on Mg and Zn availability.
