Alterations in Gut Microbiome Seen Early in Inflammatory Bowel Disease

MONDAY, Jan. 5, 2026 (HealthDay News) — Alterations in the gut microbiome are seen at the earliest stage of inflammatory bowel disease (IBD), according to a review published online Dec. 23 in Gastroenterology.

Peter Rimmer, B.M.B.S., Ph.D., from the University of Sydney, and colleagues conducted a systematic review to describe gut microbiome signatures in treatment-naïve new-onset IBD. Thirty-six eligible studies were identified: 18 and 24 contributed to bioinformatic reanalysis and supplementary meta-analysis, respectively. Samples were included from 1,743 patients: 678 with Crohn disease (CD), 399 with ulcerative colitis (UC), 130 healthy controls (HCs), and 405 symptomatic controls (SCs); 990 were biopsy samples.

The researchers observed reduced alpha diversity for pediatric UC versus SCs, adult CD and UC versus HCs, and pediatric SCs versus HCs in feces, and for CD versus SCs, CD versus UC, and UC versus SCs in pediatric biopsy samples. Clear distinctions were seen between fecal and mucosal biopsy communities in beta diversity, which was least evident in UC, in addition to community separation by geography. Depletion of anerobic and enrichment of aerobic and facultative anerobic bacteria were seen in multivariate modeling, along with enrichment of oral genera across both CD and UC.

“This research gives us a clearer picture of what”s happening in the gut at the very start of IBD,” Rimmer said in a statement. “Our findings suggest that changes in gut oxygen levels and the migration of bacteria from the mouth to the gut may play a key role in triggering inflammation — and these patterns could pave the way for earlier diagnosis and new treatments for IBD patients.”

Several authors disclosed financial ties to the pharmaceutical industry.

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