Reinforcement of intestinal epithelial barrier by arabinoxylans in overweight and obese subjects: A randomized controlled trial: Arabinoxylans in gut barrier

Abstract

Obesity and metabolic diseases are associated with alterations in microbial composition and impaired gut barrier. Previous invitro and animal studies have shown that arabinoxylans (AX) have the potential to modulate gut microbiota and gut barrier and therefore could have a protective role. Primary aim of the study was to investigate the effect of AX on intestinal permeability. Secondary aims included the effect of AX on gene transcription and protein expression of tight junctions (TJ), intestinal microbiota composition and activity, immune response and metabolic markers in overweight and obese individuals. In this randomized, double-blind, placebo-controlled trial, 47 overweight subjects were randomly assigned to groups receiving 7.5g/d AX (n=16), 15g/d AX (n=17) or 15g/d placebo (n=14) for 6wks. Intestinal permeability was investigated using a multi-sugar test. Sigmoid colon tissue was obtained from a subgroup (n=26) for analyzing gene transcription and mucosal expression of TJ proteins. Fecal samples were collected to assess microbial composition and activity. Furthermore, the production of cytokines by stimulated peripheral blood mononuclear cells (PBMCs) was examined. Blood was also sampled for measuring metabolic markers. No significant changes in gastrointestinal permeability and TJ protein expression were observed after 6wks AX supplementation compared to placebo. However, gene transcription of occludin was upregulated in the 7.5g AX group, and transcription of claudin-3 and claudin-4 were upregulated in the 15g AX group compared to placebo. Furthermore, fecal microbiota diversity was decreased after 6wks 15g AX treatment, but no change in relative abundance of dominant phyla was observed. AX intake significantly decreased fecal pH and increased fecal concentrations of total SCFAs, acetate, propionate and butyrate, compared to placebo. Additionally, a decreased TNFα production by stimulated PBMCs was observed after 15g AX treatment. No changes in metabolic markers were detected. Regular consumption of AX resulted in a more beneficial fermentation profile in overweight and obese individuals. Further studies are required to assess whether such fermentation profile will translate into improved gut barrier function and immune health. The trial has been registered at ClinicalTrials.gov with study ID number NCT01877044.