1046 A Diet Rich in Arabinoxylan and Resistant Starch Increases Colonic Butyrate Concentration and Expression of Tight Junction Protein Occludin and Decreases Fecal Calprotectin in Subjects With Metabolic Syndrome

Abstract

Obesity is associated with alterations in microbial composition and an impaired gut barrier function. Defects in preserving the integrity of the gut barrier may contribute to chronic low-grade inflammation which is thought to play a role in the development of chronic metabolic diseases. Arabinoxylans (AXs) are the most abundant non-digestible carbohydrates present in wheat. AXs are thought to exert prebiotic effects although this has not yet been established. Aim of the study was to investigate the efficacy of daily AX supplementation over a 6-weeks period on gut barrier function, microbiota composition and activity, and metabolic control in overweight and obese subjects. Methods: In this randomized, doubleblind, placebo-controlled trial, 45 subjects (24 male; mean age 49.2±15.6 years; mean body mass index 31.0±2.5 kg/m2) were randomly assigned to groups that received either 7.5g/ day AX (n=14), 15g/day AX (n=17) or 15g/day placebo ((maltodextrin) n=14), respectively, for 6 weeks. Segment specific intestinal permeability was assessed with a multi-sugar test, and sigmoid colon biopsies were obtained from a subgroup of participants for analyses of gene transcription and mucosal expression of tight junction (TJ) proteins. Peripheral blood mononuclear cells (PBMCs) were isolated and cultured to determine cytokine production capacity. Fecal samples were collected to assess microbiota composition and activity. Blood was sampled for measuring concentrations of glucose, insulin and lipids. All measurements were performed at baseline and at the end of the study period. Differences between AX and placebo groups were assessed using linear mixed models. Results: AX treatment significantly increased the production of total fecal SCFAs in both the 7.5g AX and 15g AX group (p<.025). Fecal acetate concentrations were significantly higher in the 15g AX group (p= .019), and butyrate concentrations were significantly higher in the 7.5g AX group (p=.001), compared to placebo. Analyses of microbiota composition are ongoing. Gene transcription of claudin-3 was increased in sigmoid biopsies in the 15g AX group (p=.018); TJ protein expression was not altered. AX treatment did not alter intestinal permeability, cytokine production capacity of PBMCs or metabolic parameters. Conclusion : Daily AX supplementation for 6 weeks increases fecal concentrations of SCFAs, including acetate and butyrate, in overweight and obese subjects. The AX supplementation resulted in increased transcription of claudin-3, but did not induce changes in intestinal permeability or alter tight junction protein expression.