Healthcare (Commonwealth Union) – An international analysis of microbiome data has found that people newly diagnosed with inflammatory bowel disease (IBD) show a marked decline in helpful gut bacteria, alongside an increase in bacteria normally found in the mouth appearing further down the digestive tract.
According to the new global study, major shifts in gut bacteria occur at the very beginning of IBD, raising hopes for earlier diagnosis and the development of new treatment approaches.
Published today in Gastroenterology, the research was led by scientists at the University of Birmingham and is the first study to merge raw microbiome data from multiple previous studies. Researchers examined information from more than 1,700 children and adults in 11 countries, all of whom had recently been diagnosed and had not yet begun treatment.
The results show that individuals with the two most common forms of IBD — Crohn’s disease and ulcerative colitis — experience a loss of beneficial anaerobic bacteria that play a key role in breaking down complex carbohydrates. At the same time, there is an increase in oxygen-tolerant bacteria, typically associated with the mouth, that migrate and persist in the gut.
Dr Peter Rimmer, from the University of Birmingham and Consultant Gastroenterologist at University Hospitals Birmingham NHS Foundation Trust, and joint lead author of the study, indicated that despite the facts that earlier studies have hinted that IBD may involve a reduction in helpful anaerobic bacteria and a shift towards oxygen-tolerant microbes, this is the first research to show these changes so clearly at the point when the disease begins, using evidence drawn from multiple international datasets.
“This research gives us a clearer picture of what’s happening in the gut at the very start of IBD. 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.”
The findings lend weight to the “oxygen hypothesis,” which suggests that higher oxygen levels in the gut lining can upset the microbiome’s fragile equilibrium and help drive disease. The study also points to the appearance of normally oral bacteria, including Granulicatella and Haemophilus, in the gut—organisms that could represent new avenues for treatment or prevention.
The study found that people with IBD have reduced levels of bacteria that help limit inflammation, alongside an early increase in oxygen-tolerant microbes, including species more commonly found in the mouth. Researchers also identified notable differences between stool and biopsy samples, as well as between children and adults, while microbiome patterns varied across regions of the world—highlighting the importance of globally representative data. The analysis further revealed wide variation in the methods used to study the microbiome, pointing to an urgent need for greater standardisation in the field. Together, the findings could pave the way for new diagnostic tools to detect IBD earlier and support the development of treatments that target the microbiome or alter oxygen levels in the gut, particularly for newly diagnosed patients and those at increased risk.
Professor Tariq Iqbal, who is the joint senior author of the study, Director of the University of Birmingham’s Microbiome Treatment Centre, and the theme lead for the NIHR Birmingham Biomedical Research Centre’s Oral, Intestinal and Systemic Health research theme pointed out that the findings show the value of joining hands for the study in the microbiome field. Professor Iqbal indicated that by adding together data from across the world and advanced bioinformatics, they woving moving closer to personalised, non-drug therapies that have the ability to transform the way chronic gut conditions like IBD are treated.
