Effect of Bifidobacterium longum and inulin on gut bacterial metabolism and carcinogen-induced aberrant crypt foci in rats

作者：I.R. Rowland · 发表于：Carcinogenesis · 年份：1998 · DOI：10.1093/carcin/19.2.281 · 被引用次数：469 · 研究领域：Microbial Metabolites in Food Biotechnology、Gut microbiota and health、Probiotics and Fermented Foods

The effect of Bifidobacterium longum (4 x 10(8) viable cells/g diet) and a derivative of inulin ('Raftiline HP'; 5% w/w in diet) on colonic aberrant crypt foci (ACF) induced by the colon carcinogen azoxymethane (AOM) has been studied. The concentration of ammonia, a putative tumour promoter produced by bacterial degradation of protein and urea, and the activities of certain bacterial enzymes thought to play a role in colon carcinogenesis, beta-glucuronidase and beta-glucosidase were also assayed. Consumption of either B. longum or inulin was associated with a decrease (26 and 41%, respectively) in AOM-induced small ACF (i.e. those comprising 1-3 aberrant crypts per focus). Combined administration of the bifidobacterium and inulin resulted in more potent inhibition of ACF than administration of the two separately, achieving 80% inhibition of small ACF. Furthermore, the combined administration significantly decreased the incidence (by 59%) of large ACF (>4 aberrant crypts per focus), which are considered to be predictive of eventual tumour incidence. Since the dietary treatments were started 1 week after the carcinogen dose, the results suggest that B. longum and inulin may be affecting the early promotion phase of the carcinogenic process. Consumption of diets containing B. longum, inulin or both were also associated with decreases in beta-glucuronidase activity and ammonia concentration in the caecal contents. Both these factors have been associated with carcinogenesis of the...