Microbiome May Predict Fiber-Induced Bloating

TOPLINE:

About 1 in 5 patients with functional bloating experienced worsening of symptoms from common fermentable fibers; those patients had a higher baseline symptom burden, increased abdominal girth after fiber intake, and distinct gut microbiome signatures.

METHODOLOGY:

Fermentable fibers such as fructans and alpha-galacto-oligosaccharides (alpha-GOS) are commonly associated with bloating in susceptible individuals despite fulfilling the criteria for prebiotics.
Researchers conducted a randomized crossover trial to identify individuals with functional bloating who develop symptoms to these fermentable fibers and to evaluate clinical, dietary, microbial, and fermentation factors underlying this response.
They analyzed data of 40 patients with functional bloating (median age, 29.5 years; 92.5% women) who received 8 g/d of fructans or alpha-GOS for 7 days with a washout period of 21 days in between; 39 participants completed both the challenges.
Clinical profiles were assessed with validated symptom instruments, 3-day food diaries, Bristol stool form assessment, tape-measured abdominal girth, appetite and body composition measures, and baseline visceral sensitivity testing; gut microbiome composition and activity were characterized by shotgun metagenomic and metatranscriptomic sequencing.
The primary endpoint was bloating symptoms during the final 3 days of each fiber challenge; responders were participants reporting inadequate relief of bloating symptoms on at least 2 of the final 3 days.

TAKEAWAY:

Overall, 17.9% of patients responded to fructans, 20% responded to alpha‑GOS, and 7.7% responded to both; responders experienced more days with inadequate relief of bloating during the corresponding fiber challenge than nonresponders (P < .001 for both fibers).
Before undertaking the challenge, fructan responders reported more days with inadequate relief (P = .017), and alpha-GOS responders had greater baseline bloating (P = .011); both groups also showed higher abdominal girth after completing fiber challenges (fructans, P = .009; alpha-GOS, P = .030).
Fructan responders exhibited higher carbohydrate-active enzyme diversity both at baseline and after the completion of challenge (adjusted P < .05 for both); alpha-GOS responders showed specific taxonomic differences rather than diversity differences and an increased postchallenge metatranscriptomic signal for gamma-aminobutyric acid degradation (adjusted P = .041).
Alpha-GOS responders had significantly higher fasting breath hydrogen levels before the challenge than nonresponders (P = .011 ).

IN PRACTICE:

“A higher burden of GI [gastrointestinal] symptoms predicts clinical response to fermentable fibers in functional bloating, while for α-GOS, higher repeated fasting breath H₂ [hydrogen] is also a predictor. Gut microbiome function and fermentation is associated with functional bloating; however, further investigations are required to draw firm conclusions for the microbial influence in this interplay,” the authors of the study wrote.

SOURCE:

This study was led by Dominic N. Farsi, PhD, King’s College London, London, England. It was published online in The American Journal of Gastroenterology.

LIMITATIONS:

The small number of responders limited statistical power. Stool-based metatranscriptomics may not have fully reflected colonic metabolic activity or accounted for spatial variation along the gastrointestinal tract.

DISCLOSURES:

This study was funded by Danone Research & Innovation. Six authors declared being current or former employees of the funding organization. Some others reported receiving honoraria, research funding, and consultancy or speaker fees from commercial sponsors; one author reported being the co-founder of a food company and/or holding related patents.

This article was created using several editorial tools, including AI, as part of the process. Human editors reviewed this content before publication.