Effects of purified cellulose and pectin fiber diets on mutagenicity of feces and luminal contents of stomach, small and large bowel in rats
Kuhnlein, U.; Gallagher, R.; Freeman, H.J.
Clinical and Investigative Medicine. Medecine Clinique et Experimentale 6(4): 253-260
1983
ISSN/ISBN: 0147-958X PMID: 6323077 Document Number: 199650
The mutagenicity in extracts of fecal pellets and luminal contents obtained from specific sites along the gastrointestinal tract was examined in male Wistar rats fed a chemically-defined fiber-free diet or nutritionally and calorically equivalent diets containing different amounts of either cellulose or pectin (4.5 or 9.0%) or a mixture of cellulose and pectin (4.5% each). Mutagenicity was measured with the fluctuation test for weak mutagens using Salmonella typhimurium strains TA98 and TA1535 as test organisms. Dietary fiber reduced the mutagenicity of fecal pellets from most of the animals. However, given the number of animals studied, the reduction was only significant for the 9.0% pectin diet (TA98), the 9.0% cellulose diet (TA1535) and the mixed fiber diet (TA1535). Analysis of the contents of stomach, distal small bowel, cecum and colon after a period of 8 weeks on a fiber-free diet revealed that the distal small bowel content had a mutagen concentration that was several times that at any other site. The mutagenicity of the small bowel content of animals on diets containing either 9.0% cellulose or 9.0% pectin was significantly lower than that of animals on a fiber-free diet, as assayed by either of the test strains of S. typhimurium. A similar reduction was detected in animals on the 4.5% cellulose or 4.5% pectin diet by test strain TA1535, but a diet containing a mixture of the same fiber polymers did not reduce the mutagenicity of the small bowel content. The mutagenicity of the contents of the stomach, cecum and colon was not significantly influenced by dietary fiber.