Effect of Sodium Phytate and Phytin on the Absorption and Organ Concentration of Several Minerals in Rats

抄録

The effects of sodium phytate or phytin administration on several mineral utilizations in rats were examined. Eighteen male 4-week-old Wistar/ST rats were divided into 3 groups. One group (control group) was fed a basal AIN93G diet, the other two groups (SP group and phytin group) were fed the basal diet containing sodium phytate (1.0wt%) or rice bran-derived phytin (1.0wt%), respectively, for 4 weeks. Because the phytin used contained magnesium, zinc, and manganese, the phytin group consumed more of these minerals than the other two groups. The SP group excreted more magnesium in their feces and had a lower apparent absorption than the control group, which had a similar magnesium intake. In addition, the SP group had lower zinc concentrations in the serum and several organs than the control group. There was also a trend toward lower serum and organ zinc concentrations in the phytin group compared to the control group, but the only significant difference was in the femoral zinc concentration. The phytin group had lower apparent iron absorption and lower serum and organ iron concentrations than the other two groups. The serum phosphorus concentrations and urinary phosphorus excretion were increased in the SP and phytin groups. These results indicated that 1) phytic acid inhibits the absorption of magnesium and zinc, 2) minerals bound to phytin, possibly manganese, inhibit iron absorption, 3) phytic acid is partially hydrolyzed in the digestive tract, phosphoric acid and the minerals bound to phytic acid are released and utilized.