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.