[The effects of food ingredients on non-heme iron absorption in rats and the inhibitory mechanism of soy protein isolate].

The effects of food ingredients on iron absorption were investigated by means of long and short term experiments after 59Fe material administration through stomach tubes to male Wistar rats of 200 to 300 grams body weight. The ingredients tested were casein, poultry meat, fish meat and soy protein isolate (SPI) which were contained by 24% in the synthetic food as the protein source. In the former experiment, the amounts of 59Fe incorporation into the blood after 7 days and also 59Fe excreted in feces during the same period were determined, whereas in the latter experiment 59Fe contained in the blood and scraped intestinal mucosa was measured after 3 hours. The following results were obtained. Although iron deficient rats showed a higher absorption rate than the iron adequate rats on a comparable diet, there was no difference in the rate of iron absorption, irrespective of diet in experiments for iron deficient rats. On the contrary, iron absorption by iron adequate rats depended on the diets tested. The rat group which received poultry meat or fish meat as the protein source showed a high rate of absorption, while the group which received SPI showed markedly low absorption. The effect of the SPI diet was also found in the low 59Fe activity in the scraped mucosa and liver ferritin. The inhibitory effect of the SPI diet on iron absorption was significantly recovered by adding galactose