12/03/2026
One of the most overlooked contributors to gut dysbiosis is the health of the oral microbiome.
Digestion does not begin in the stomach, it begins in the mouth, which hosts one of the most complex microbial ecosystems in the human body.
The oral cavity contains over 700 microbial species, and every day we swallow billions of these microbes through saliva.
Under healthy conditions, the oral microbiome exists in balance with the immune system and digestive tract. However, when imbalances in the oral microbiome develops, certain bacteria can migrate into the gastrointestinal tract and contribute to microbial imbalance in the gut.
This process is increasingly recognised in research as part of the oral - gut microbiome axis.
In stool testing, we sometimes observe bacteria that are typically associated with the oral microbiome appearing in the intestinal microbiota.
Examples include species from genera such as:
• Streptococcus�• Rothia�• Corynebacterium
These organisms are normal inhabitants of the oral cavity, but when present in elevated levels in the gut they can contribute to microbial imbalance, inflammatory signalling, and disruption of the intestinal ecosystem.
The presence of oral - associated microbes in stool testing can therefore indicate that oral microbial imbalance may be contributing to gut dysbiosis.
Firstly, this is why testing can be so beneficial as very often we have to look at the broad microbial ecosystem of the body when we want to restore gut health.
Supporting oral microbiome balance and oral hygiene can sometimes play an important role in restoring microbial balance within the gut.
In tomorrow’s post, I’ll share a case study on this and then later this week some practical steps that support the oral microbiome naturally.