Effect of short-chain fructooligosaccharides and cellulose on cecal enzyme activities in rats

The effect of fructooligosaccharides (FOS) on cecal enzyme activity was studied. Adult male Wistar rats were fed a fiber-free diet supplemented with 5% cellulose, a 5% mixture (1:1) of cellulose and FOS or 5% FOS as a source of fiber for 4 weeks. The cecal content was used to measure azoreductase, beta-glucuronidase, beta-glucosidase, nitrate reductase and nitroreductase activities. Cellulose-fed diet increased significantly body weight gain, food intake and fecal stool weight compared to FOS-fed diet. No differences in food intake between FOS-containing diets were found. FOS-containing diets showed statistically higher weight of cecal content and weight of cecal wall compared with the cellulose group. There were significant differences in cecal enzyme activities between cellulose-fed rats and FOS-fed rats. Cellulose-FOS-fed diet decreased significantly nitroreductase, beta-glucuronidase and beta-glucosidase enzymes, but did not differ statistically in azoreductase and nitrate reductase compared with the control group. FOS-fed diet increased significantly reductive enzymes and decreased hydrolytic enzymes compared with the cellulose group. The incorporation of cellulose in diet seems to affect the prebiotic effect of FOS, since both cellulose and FOS are possible substrates for bifidobacteria proliferation. The results suggest that a mixture of cellulose and FOS as a source of dietary fiber could have a healthier effect on bacterial enzyme activities than each type of dietary fiber alone.