The finding could help doctors diagnose inflammatory bowel disease early, and the researchers added that the finding could potentially boost efforts to find new treatments for the condition.
The researchers found that people with the most common types of inflammatory bowel disease, including Crohn's disease and ulcerative colitis, typically lose beneficial anaerobic bacteria that help us digest complex carbohydrates. (Anaerobes means that these bacteria live and grow where there is no oxygen.)
At the same time, patients experienced an increase in oxygen-tolerant bacteria that are naturally found in the mouth but have been transferred to the gut.
"This is the first study to clearly show these changes early in the disease," said Dr. Peter Reimer, a senior researcher at the University of Birmingham in the United Kingdom, in a news release.
The researchers said the results support the “oxygen hypothesis” of inflammatory bowel disease, a theory that suggests that increased oxygen in the gut lining can disrupt a person’s microbiome and lead to disease.
“This research gives us a clearer picture of what’s happening in the gut at the very beginning of inflammatory bowel disease,” Reimer said. “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 the development of inflammation, and these patterns could pave the way for early diagnosis and new treatments for inflammatory bowel disease patients.”
For the new study, the researchers analyzed data from more than 1,700 children and adults in 11 countries who had recently been diagnosed with inflammatory bowel disease.
The data was drawn from 36 previous studies.
The results specifically highlighted the presence of oral bacterial species such as Granulocyte and Haemophilus in the guts of people with inflammatory bowel disease.
The researchers said that treating these bacteria – or preventing them from accumulating in a person’s gut – could help prevent inflammatory bowel disease.
“Other new treatments could focus on reducing oxygen levels in the gut or increasing the number of healthier bacteria in the gut,” the team added.