(P19-018-25) Fecal Fermentation and Microbial Adaptation to Arabinoxylan: Insights From a Pilot Study in Inactive Inflammatory Bowel Disease

Objectives: Inflammatory bowel disease (IBD) is linked to abnormal gut microbial communities with reduced fiber-utilizing taxa and elevated production of harmful nitrogenous metabolites. Arabinoxylans (AX) are a hemicellulose fiber found in whole grains, known to support the growth of beneficial bacteria and promote production of anti-inflammatory short chain fatty acids (SCFA). However, whether patients with IBD and abnormal gut microbiota can also benefit from AX supplementation has not been studied. To this end, we aimed to investigate whether daily supplementation with a soluble, arabinoxylan-rich (AX) fiber enhances microbial fermentation in batch fecal cultures as an indicator of adaptation of the microbiome to AX in IBD and healthy subjects.

Methods: Four subjects with IBD and two non-IBD controls participated in a, randomized, single-blind, cross-over trial. Participants consumed 25g/day of either corn bran AX (~81% AX) or maltodextrin for four weeks, with a four-week washout. Batch fermentations were inoculated with frozen stool collected at baseline and post-intervention using 1mL fermentation medium containing a) no substrate or 15mg in vitro digested AX and b) 3g/L or 0.9g/L peptone. Fermentations proceeded for 16h at 37°C in an anaerobic chamber before determining pH as a measure of fermentative activity.

Results: Stool SCFA concentrations did not change from baseline after consuming AX for four weeks, but fecal calprotectin decreased in 5/6 subjects. In the in vitro experiments, we observed that specific fermentation patterns were subject-dependent (p < 0.001), reflecting microbiome variation. pH was significantly lower in AX vs no substrate fermentations (6.26 ± 0.85 vs. 5.55 ± 0.87; p< 0.001) and in post-intervention fecal fermentations (6.11 ± 0.89 vs. 5.70 ± 0.93; p< 0.001), with no interaction between these effects. Protein nitrogen content had no measurable effect on pH. 

Conclusions: Our findings demonstrate that both IBD and non-IBD gut microbiota ferment AX, with enhanced fermentative activity following AX supplementation. This study highlights the potential of AX as a prebiotic intervention in IBD and underscores the need for further investigation into microbiome functional shifts using metabolomics.

Funding Sources: None