EFFECTS OF DIFRUCTOSE ANHYDRIDE-III ON CALCIUM-ABSORPTION IN SMALL AND LARGE-INTESTINES OF RATS

Difructose anhydride III (DFA III; di-D-fructo-furanose 1,2':2,3' dian hydride) was prepared from inulin with Arthrobacter sp. H65-7 inulin f ructotransferase (depolymerizing) (inulase II; EC 2.4.1.93). DFA III i s not hydrolyzed by enzymes in the small intestine, but is metabolized by microorganisms in the large intestine. We investigated the effects of DFA III on calcium absorption in two experiments. In the in vivo e xperiment, we examined the effects of DFA III, fructooligosaccharides, and raffinose on calcium absorption in male Sprague-Dawley rats 5 wee ks old at start of the experiment and given feed containing 3% of one of these oligosaccharides for two weeks. The apparent calcium absorpti on was significantly higher in rats fed any of these oligosaccharides than in control rats, and the increase with DFA III was the greatest. Absorption in both the small and large intestines was affected. In rat s fed DFA m, the cecal wall thickened and soluble calcium and the amou nts of some organic acids were higher than in the control groups. In a n in vitro experiment with everted jejunal and ileal sacs of rats, cal cium absorption was higher when DFA III was present in the mucosal flu id at all concentrations tested (up to 200 mM). In the jejunal sacs, t he increase in calcium absorption depended on the DFA III concentratio n. In the heal sacs, the absorption was maximum at 50 mM DFA III and d id not increase further at higher concentrations. These results indica te that intact DFA III stimulates calcium absorption in the small inte stine, and that cecal fermentation of DFA In may contribute to the inc rease in calcium absorption by the large intestine.