EFFECTS OF FRUCTOOLIGOSACCHARIDES ON THE ABSORPTION OF MAGNESIUM AND CALCIUM BY CECECTOMIZED RATS

We reported previously that feeding of fructooligosaccharides (FO) inc reased the apparent absorption of calcium (Ca), magnesium (Mg) and pho sphorus (P) in rats. We suggested that there was an important correlat ion between this phenomenon and fermentation of FO in the large intest ine. However the precise mechanism remained to be characterized. There fore, we performed a mineral-balance study to identify the segment of lumen in which FO affects mineral absorption, using cecectomized rats. Sham-operated rats and cecectomized rats were fed a control diet (wit hout FO) or an FO-diet (containing 50 g of FO per kg of feed) for 28 d ays. Feeding of the FO-diet decreased the lumina pH in the cecum and c olon in the sham-operated rats. In the cecectomized rats, feeding of t he FO-diet also decreased the lumina pH in the colon. Thus, FO was fer mented in the colon of the cecectomized rats. However the acid composi tion of feces was altered by cecectomy. Feeding of the FO-diet increas ed the absorption of Ca and Mg in the sham-operated mts. In the cecect omized rats, the FO-diet increased the absorption of Mg but did not in crease the absorption of Ca. These results suggest the mechanisms for the absorption of Ca and Mg when rats are fed an FO are different.