Diets enriched with cranberry beans alter the microbiota and mitigate colitis severity and associated inflammation.

Monk, J.M., Lepp, D., Zhang, C., Wu, W., Zarepoor, L., Lu, J., Pauls, K.P., Tsao, R., Wood, G.A., Robinson, L.E., and Power, K.A. (2016). "Diets enriched with cranberry beans alter the microbiota and mitigate colitis severity and associated inflammation.", Journal of Nutritional Biochemistry, 28, pp. 129-139. doi : 10.1016/j.jnutbio.2015.10.014  Access to full text

Abstract

Common beans are rich in phenolic compounds and non-digestible fermentable components, which may help alleviate intestinal diseases. We assessed the gut health priming effect of a 20% cranberry bean flour diet from two bean varieties with differing profiles of phenolic compounds [darkening (DC) and non-darkening (NDC) cranberry beans versus basal diet control (BD)] on critical aspects of gut health in unchallenged mice, and during dextran sodium sulphate (DSS)-induced colitis (2% DSS w/v, 7 d). In unchallenged mice, NDC and DC increased i) cecal short chain fatty acids, ii) colon crypt height, iii) crypt goblet cell number and mucus content and iv) Muc1, Klf4, Relmβ, and Reg3γ gene expression versus BD, indicative of enhanced microbial activity and gut barrier function. Fecal 16S rRNA sequencing determined that beans reduced abundance of the Lactobacillaceae (Ruminococcus gnavus), Clostridiaceae (Clostridium perfringens), Peptococcaceae, Peptostreptococcaceae, Rikenellaceae and Pophyromonadaceae families, and increased abundance of S24-7 and Prevotellaceae. During colitis, beans reduced i) disease severity and colonic histological damage, ii) increased gene expression of barrier function promoting genes (Muc1-3, Relmβ, and Reg3γ) and iii) reduced colonic and circulating inflammatory cytokines (IL-1β, IL-6, IFNγ and TNF-α). Therefore, prior to disease induction, bean supplementation enhanced multiple concurrent gut health promoting parameters that translated into reduced colitis severity. Moreover, both bean diets exerted similar effects, indicating that differing phenolic content did not influence the endpoints assessed. These data demonstrate a proof-of-concept regarding the gut-priming potential of beans in colitis, which could be extended to mitigate the severity of other gut barrier-associated pathologies.

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