Effect of Dietary Fibers on Cecal Microbiota and Intestinal Tumorigenesis in Azoxymethane Treated A/J Min/+ Mice

Abstract

Foods naturally high in dietary fiber are generally considered to protect against development of colorectal cancer (CRC). However, the intrinsic effect of dietary fiber on intestinal carcinogenesis is unclear. We used azoxymethane (AOM) treated A/J Min/+ mice, which developed a significantly higher tumor load in the colon than in the small intestine, to compare the effects of dietary inulin (IN), cellulose (CE) or brewers spent grain (BSG) on intestinal tumorigenesis and cecal microbiota. Each fiber was tested at two dose levels, 5% and 15% (w/w) content of the AIN-93M diet. The microbiota was investigated by next-generation sequencing of the 16S rRNA gene (V4). We found that mice fed IN had approximately 50% lower colonic tumor load than mice fed CE or BSG (p<0.001). Surprisingly, all three types of fiber caused a dose dependent increase of colonic tumor load (p<0.001). The small intestinal tumor load was not affected by the dietary fiber interventions. Mice fed IN had a lower bacterial diversity than mice fed CE or BSG. The Bacteroidetes/Firmicutes ratio was significantly (p = 0.003) different between the three fiber diets with a higher mean value in IN fed mice compared with BSG and CE. We also found a relation between microbiota and the colonic tumor load, where many of the operational taxonomic units (OTUs) related to low tumor load were significantly enriched in mice fed IN. Among the OTUs related to low tumor load were bacteria affiliated with the Bacteroides genus. These results suggest that type of dietary fiber may play a role in the development of CRC, and that the suppressive effect of IN on colonic tumorigenesis is associated with profound changes in the cecal microbiota profile.

Effects of Prebiotic Fiber Xylooligosaccharide in Adenine‐Induced Nephropathy in Mice

“…This observation indicates that greater microbe richness may not be a definitive sign of a healthy gut microbiota, but could be due to overgrowth of a variety of harmful bacteria or archaea . In addition, our results are consistent with other publications showing a decrease of alpha diversity with the supplementation of readily fermentable fiber . We hypothesize that prebiotic fibers such as XOS strongly favor gut bacteria with saccharide‐degrading ability that are commonly found in the healthy microbiota.…”

Deficiency of Dietary Fiber in Slc5a8-Null Mice Promotes Bacterial Dysbiosis and Alters Colonic Epithelial Transcriptome towards Proinflammatory Milieu

“…Hamilton et al [37] have reported that increased Akkermansia abundance in colon is associated with decreased thickness of the mucus layer and also with decreased number of mucin-producing goblet cells. Furthermore, Akkermansia spp., Desulfovibrio spp., and phylum Prevotella have more tendency to bind to inflamed colon compared to healthy colon [38,39]. We found in our study that the mucolytic bacteria Akkermansia are in higher abundance in Slc5a8-null mice when fed the fiber-free diet.…”

Effect of feeding duration of <i>Spirulina platensis</i> on growth performance, haematological parameters, intestinal microbial population and carcass traits of broiler chicks

“…The heavier caecum may be associated with the improved fermentation function of broiler chicks (Clench & Mathias, 1995). The definite explanation for the enhanced weight of caecum in broilers fed S. platensis for 35 days was not known, but it was possible that long-term feeding of S. platensis led to greater fibre intake, and thus resulted in heavier caeca (Moen et al, 2016). Note that S. platensis in this study contained 34.2% of fibre.…”