Your mouth may reveal more about your overall health than you realise. While many people associate brushing, flossing and dental check-ups with having a healthy smile, experts say oral health is also closely connected to the digestive system.
The mouth and gut are home to complex communities of microorganisms known as the microbiome. These bacteria and other microbes play important roles in maintaining a healthy balance in the body. When that balance is disrupted, it may affect more than just your teeth and gums.
In an article published by News24 on 28 October 2026, experts Jemma van den Berg and Madeleine Kietzmann explored how oral bacteria, food choices and everyday habits can influence gut health.
Understanding the connection between your mouth and gut
The digestive process begins in the mouth. As food is chewed, saliva helps break it down before it travels through the digestive system.
However, saliva also contains microorganisms that can be swallowed and introduced into the gut. Some of these bacteria may contribute positively to the body’s microbial environment, while others can cause problems when they become too dominant.
According to research, the oral microbiome is made up of hundreds of microbial species living on the teeth, tongue, gums and other surfaces inside the mouth.
Scientists are increasingly investigating how these communities interact with microorganisms in the digestive system. The relationship is important because an imbalance in one area may influence the other.
How oral bacteria can affect the gut
Not all bacteria in the mouth are harmful. Many contribute to a healthy microbial environment and support the body’s natural defences.
However, certain harmful bacteria associated with gum disease and poor oral health may enter the digestive system.
Research published in January 2026 by scientists associated with King’s College London found that particular bacteria originating in the mouth could move into the gut in people with advanced chronic liver disease.
The study examined saliva and stool samples from 86 patients. Researchers identified bacterial species, including Veillonella and Streptococcus, that appeared to move from the mouth into the gut.
Some of these bacteria were associated with damage to the intestinal barrier, which normally helps prevent harmful substances from entering the bloodstream.
The researchers said the findings could help develop future approaches to managing complications associated with advanced liver disease. However, the study does not mean that ordinary oral bacteria will cause liver disease in healthy people.
Your diet plays an important role
Food choices can influence the balance of microorganisms in both the mouth and digestive system.
Diets containing large amounts of added sugar may encourage harmful oral bacteria, increasing the risk of tooth decay and other dental problems.
On the other hand, fibre-rich foods such as vegetables, fruit, legumes and whole grains help support beneficial gut bacteria.
Fermented foods, including yoghurt, kefir, sauerkraut and kimchi, can also provide microorganisms that may support gut health.
Drinking enough water is another important habit. Saliva helps protect the mouth by washing away food particles and supporting a balanced oral environment.
Everyday habits that may affect your microbiome
Experts recommend maintaining good oral hygiene as part of an overall approach to health.
Brushing twice daily with fluoride toothpaste, cleaning between the teeth and attending regular dental check-ups can help reduce plaque and gum inflammation.
Smoking and vaping may also negatively affect the oral microbiome. These habits can reduce saliva production and interfere with the mouth’s natural protective mechanisms.
Stress is another factor worth considering. It can influence saliva production and has been associated with changes in both oral and gut microbial communities.
People should also avoid assuming that stronger mouthwash is always better. Certain antiseptic products can affect beneficial bacteria as well as harmful microorganisms, so dental products should be selected appropriately.
Why the mouth deserves more attention
The growing understanding of the relationship between oral and gut health shows why dental care should not be viewed as separate from general wellbeing.
Persistent bad breath, bleeding gums, tooth decay and ongoing digestive discomfort deserve attention, although none of these symptoms alone can confirm an imbalance in the gut microbiome.
Anyone experiencing persistent digestive symptoms should seek advice from a qualified healthcare professional rather than attempting to diagnose a condition through their mouth.
Ultimately, maintaining a balanced diet, drinking enough water, avoiding tobacco and practising consistent dental hygiene can support oral health while contributing to wider wellbeing.
The message is simple: looking after your mouth is not only about protecting your teeth. It is also one part of taking care of your body as a whole.
Oral and gut health remain a growing research focus
The relationship between the oral microbiome and digestive health continues to attract scientific interest. Researchers are investigating how bacteria from the mouth interact with the gut and whether these findings could help improve disease prevention and treatment.
News24 highlights the mouth-gut connection
News24 publishes an expert-focused article featuring Jemma van den Berg and Madeleine Kietzmann, explaining how oral bacteria, diet and everyday habits may influence digestive health.
Researchers publish findings on oral bacteria and liver disease
King’s College London reports research showing that certain bacteria originating in the mouth can colonise the gut in people with advanced chronic liver disease. The findings highlight a possible connection between oral bacteria, intestinal barrier damage and liver complications.