Scientists studied gut bacteria in nearly 1,800 people who were just diagnosed with inflammatory bowel disease (IBD) but hadn’t started treatment yet. They found that people with IBD have fewer ‘good’ bacteria that need oxygen-free environments and more bacteria that can survive with oxygen, including mouth bacteria that shouldn’t be in the gut. This pattern was similar in both main types of IBD - Crohn’s disease and ulcerative colitis. These findings could help doctors diagnose IBD earlier and develop new treatments that focus on fixing the gut bacteria balance.

The Quick Take

  • What they studied: How gut bacteria differ in people newly diagnosed with inflammatory bowel disease compared to healthy people
  • Who participated: 1,743 people including 678 with Crohn’s disease, 399 with ulcerative colitis, and 535 control participants from 36 different studies
  • Key finding: People with IBD have fewer beneficial oxygen-hating bacteria and more harmful oxygen-tolerant bacteria, including mouth bacteria in their gut
  • What it means for you: If you have IBD symptoms, gut bacteria testing might help with earlier diagnosis, and future treatments may focus on restoring healthy bacteria balance

The Research Details

This was a systematic review and meta-analysis, which means researchers gathered data from 36 existing studies and reanalyzed them using the same methods. They looked at both stool samples and tissue samples taken directly from the intestines of people who had just been diagnosed with IBD but hadn’t started any treatments yet. The researchers used advanced computer programs to identify and count different types of bacteria in these samples.

This approach is important because it combines results from many smaller studies to create a much larger, more reliable picture. By only including people who hadn’t started treatment yet, the researchers could see the true bacterial changes caused by IBD, not changes caused by medications.

The study included nearly 1,800 people from multiple countries and used standardized analysis methods. However, the individual studies varied in their methods, and the researchers had to account for these differences in their analysis.

What the Results Show

The most striking finding was a clear pattern of bacterial imbalance in people with IBD. Those with the condition had significantly fewer anaerobic bacteria - the ‘good’ bacteria that thrive in oxygen-free environments and help maintain gut health. At the same time, they had more aerobic and facultative anaerobic bacteria, which can survive in the presence of oxygen and are often associated with inflammation. Perhaps most surprisingly, people with IBD had higher levels of bacteria normally found in the mouth, suggesting these oral bacteria had migrated to and colonized the gut. This pattern was consistent across both major types of IBD: Crohn’s disease and ulcerative colitis.

The researchers found that bacterial diversity was generally lower in people with IBD, meaning they had fewer different types of bacteria overall. The differences were most pronounced in stool samples from adults and tissue samples from children. Geographic location also influenced bacterial communities, suggesting that environmental factors play a role in gut bacteria composition.

This study confirms and strengthens previous research suggesting that IBD involves major disruptions to the gut microbiome. However, this is one of the largest analyses to focus specifically on treatment-naive patients, providing clearer evidence that these bacterial changes are part of the disease process rather than side effects of treatment.

The study combined data from different research groups using various collection and analysis methods, which could introduce some inconsistencies. Most participants were from Western countries, so the findings may not apply to all populations. The study also couldn’t determine whether the bacterial changes cause IBD or result from it.

The Bottom Line

While this research is promising for future diagnostic and treatment approaches, it’s not yet ready for clinical use. People with IBD should continue following their doctor’s treatment plans. Those with IBD symptoms should discuss them with healthcare providers, as gut bacteria testing may become part of diagnosis in the future.

This research is most relevant for people with IBD symptoms, those with family history of IBD, and anyone interested in gut health. However, the findings are still being developed into practical applications.

It may take several years before these findings translate into new diagnostic tests or treatments that are available to patients.

Want to Apply This Research?

  • Track digestive symptoms including bowel movement frequency, consistency, abdominal pain, and any blood in stool
  • Focus on eating foods that support beneficial anaerobic bacteria, such as fiber-rich vegetables, fermented foods, and prebiotics
  • Log symptoms daily and note any patterns with diet, stress, or other factors that might affect gut bacteria balance

This research is for educational purposes only and should not replace professional medical advice. If you have symptoms of IBD or digestive issues, consult with a healthcare provider for proper diagnosis and treatment.