Preventing Inflammatory Bowel Disease by Promoting Oral Health

This transcript has been edited for clarity. 

Hello. I'm Dr David Johnson, professor of medicine and chief of gastroenterology at Eastern Virginia Medical School and of Old Dominion University in Norfolk, Virginia. 

Why is the oral microbiome important? As a gastroenterologist, why do I talk to my patients about it and recommend that you do as well? 

I’ll explain why this is an important tactic and also highlight a recent article in The American Journal of Gastroenterology that shares the results of a national cohort study investigating the association between periodontitis and inflammatory bowel disease (IBD). 

But first, let me give you some background.

An Oral Microbiome Primer 

The oral microbiome is the second largest microbial community in the human body, after the gut microbiome. It includes an array of fungi, bacteria, amoebae, flagellates, archaea, and viruses, all of which can be potential pathogens. 

Our oral microbiome can act as a facilitator not only for protection but also for aggravation when dysbiosis occurs. We may think of this primarily in terms of oral health issues, such as cavities and gingival disease. However, the systemic effects of the oral microbiome are relevant to both gastrointestinal (GI) disease and non-GI disease. 

These systemic risks occur for several reasons. 

The oral microbiome can be a source of cytokine upregulation and result in translocation of an array of bacteria, fungi, etc., and the delivery of their metabolites to individual organ systems. 

The mouth and oropharynx are a site for the upregulation of cell adhesion-like processes, activation of toll-like receptors, induction of reactive oxidative species, or generation of mutation-inducing DNA changes. 

Particularly important is the possibility for upregulation of T helper (Th) 1 and Th17, which are involved in cytokine upregulation for interferon and interleukins, respectively. 

In a healthy process, Th1 and Th17 allow us to protect ourselves. Yet, as we generate them in an aberrant way, it may result in significant consequences.

Poor Dental Health and Disease

Findings regarding dental health in the United States are generally not good, despite our parents’ firm reminders to always brush our teeth before bed. 

A 2024 oral health survey from the Centers for Disease Control and Prevention reported that nearly 21% of adults aged 20-64 years of age had one or more permanent teeth with untreated decay. Additionally, complete toothlessness (edentulism) occurred in more than 1 in 10 adults aged 65-74 years and in nearly 1 in 5 aged 75 years or older. 

This is important for GI diseases. 

There is a substantial and growing body of evidence that the oral microbiome influences diseases like colorectal cancer (as discussed in a previous presentation), esophageal cancers, Barrett's esophagus, squamous ulcer of the esophagus, metabolic-associated steatotic liver disease, and hepatocellular cancer, as well as some evidence on pancreatic ductal cancer. 

The oral microbiome’s role in the pathogenesis of IBD makes sense, given that this disease and periodontitis share overlapping features, including upregulated cytokines and chronic inflammation. 

IBD and Periodontitis: A Closer Look

With this background in mind, let’s turn to the recent study I mentioned earlier from researchers in South Korea. 

This team analyzed a cohort of over 2.2 million individuals, which captured approximately 97% of the country’s population. Periodontitis was identified by dentists during oral health screenings. The cohort was followed for a median of 17 years.

Investigators found that the incidence of Crohn's disease and ulcerative colitis were 11.6 and 32.4, respectively, per 100,000 person-years. Among those with periodontitis, the risk for Crohn's disease was nearly 30% higher (adjusted hazard ratio [aHR], 1.32) and the risk for ulcerative colitis was approximately 20% higher (aHR, 1.21).

Investigators also looked at the influence of various oral hygiene interventions on the incidence of IBD. Among those who reported frequent tooth brushing (defined as three or more times a day, which sounds like a lot), the risk of developing Crohn's disease was reduced by 12% (aHR, 0.88); however, there was no significant risk reduction for developing ulcerative colitis among these participants. 

But the main finding is that, longitudinally, the incidence of IBD was significantly associated with the presence of periodontitis. 

Prior studies also support a bidirectional association between IBD and periodontitis. In them, the authors cited animal data showing a mouse model with Crohn's disease developed periodontitis, as well as longitudinal data indicating that those with ulcerative colitis and Crohn's disease were more prone to develop periodontitis. This reflects the underlying cytokine upregulation that takes place with these conditions. 

The Importance of Oral Hygiene

How many of us take a dental history in our patients? I certainly didn't. 

We probably all consider other established risk factors for IBD, such as diet, sleep quality, and smoking, among others. To that list, we need to now add dental history and begin asking our patients about it.

I suspect that you may be the only person to ask your patients that question, especially in some rural and underserved areas with limited-to-no access to dentists. Ask your patients about the key features of good oral hygiene, including tooth brushing and flossing, as well as whether they undergo dental scaling and dental evaluations at least twice a year.

We need to start paying attention to this aspect of our patients’ health. 

Although we often focus on new interventions and medications, we should take a step back and look at what we’re missing. Oral hygiene is incredibly important. 

I personally don't recommend the use of a mouthwash because it can negatively impact the good bacteria in the mouth. However, I do recommend foundational techniques like dental brushing, flossing the teeth, and lingual brushing. The microenvironments in the mouth may not be addressed by simply brushing your teeth, as it potentially misses the sublingual and subgingival components. Implementing additional hygiene strategies can positively influence the oral microbiome, which, in turn, can make a difference in IBD and other GI diseases, not to mention non-GI diseases as well. 

Whether we practice in gastroenterology or in another field, we can start to make a difference here. Perhaps we should ask ourselves: Can we also be better dentists? This is not to replace our dentist colleagues, but rather to step in and amplify the benefits of good oral hygiene. 

Please take this into consideration the next time you have discussions around IBD as well as the multitude of inflammatory diseases that are associated with the oral microbiome. 

I’m Dr David Johnson. Thanks for listening.

David A. Johnson, MD, a regular contributor to Medscape, is professor of medicine and chief of gastroenterology at Eastern Virginia Medical School in Norfolk, Virginia, and a past president of the American College of Gastroenterology. His primary focus is the clinical practice of gastroenterology. He has published extensively in the internal medicine/gastroenterology literature, with principal research interests in esophageal and colon disease, and more recently in sleep and microbiome effects on gastrointestinal health and disease.