National Smile Month

Between 12 May and 12 June 2025, the Oral Health Foundation will raise awareness of important oral health issues.

Join the nation's biggest oral health campaign and help bring a smile to millions of people.

This year the theme for National Smile Month is Feed Your Smile.

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Your body’s overall health is interconnected, and that includes the relationship between your gut and your mouth.

What you eat can affect both your digestive system and your teeth.

A balanced diet, along with gut-friendly probiotics, can not only improve your digestion but also help maintain a healthy mouth, reducing the risk of gum disease, cavities, and bad breath.

How gut health affects oral health

The health of your gut and mouth are closely linked through the oral-gut axis, meaning what happens in your digestive system can impact your mouth, and vice versa.

Research shows that an imbalance in the bacteria in your gut can contribute to gum disease, cavities, and even conditions like oral infections. On the other hand, a healthy gut environment helps maintain a strong immune system, which supports your body’s ability to fight harmful bacteria in your mouth.

Gut bacteria and the mouth

Man with hands covering face

Bad bacteria

When there’s an imbalance of gut bacteria, harmful bacteria can make their way to your mouth, leading to gum disease and tooth decay

Woman sticking out her tongue with a heart shape on it

Good bacteria

A healthy gut promotes beneficial bacteria that can help fight harmful oral bacteria, keeping your gums and teeth healthier.

Gum holding lip with gum pain

Inflammation

An unhealthy gut can lead to inflammation, which may contribute to issues like gum disease, while a balanced gut helps manage inflammation throughout the body.

    The role of probiotics in oral health

    Probiotics are live microorganisms that provide health benefits when consumed in adequate amounts. They’re best known for supporting gut health, but they can also play a significant role in your oral health by:

    • Balancing oral bacteria: probiotics can help maintain a healthy balance of good and bad bacteria in the mouth, reducing the risk of gum disease and cavities.
    • Fighting plaque: certain probiotics have been shown to help reduce plaque buildup on teeth, preventing cavities and gum inflammation.
    • Reducing bad breath: by promoting a healthy oral microbiome, probiotics can help fight the bacteria responsible for bad breath.
    • Boosting immunity: probiotics help boost your immune system, which can strengthen your body’s natural defences against oral infections and inflammation.

    Probiotic-rich foods for a healthy mouth

    A bowl of Greek yoghurt

    Yoghurt

    Choose plain, unsweetened yoghurt with live cultures to promote healthy gut and oral bacteria.

    A wooden spoon with kefir

    Kefir

    A fermented milk drink packed with probiotics that can benefit both gut and oral health.

    A bowl of kimchi & sauerkraut

    Kimchi & sauerkraut

    Fermented vegetables that are rich in probiotics and can help balance bacteria in your mouth and gut.

    A jar of pickles

    Pickles (fermented)

    Look for naturally fermented pickles without added vinegar, as they contain beneficial bacteria.

    A bowl of miso paste

    Miso

    A fermented paste made from soybeans, miso can help support healthy gut flora, benefiting both digestion and oral health.

    How a balanced diet promotes a healthy mouth

    Your gut health is largely influenced by what you eat. A diet rich in fibre, vitamins, and minerals helps support good bacteria in both your gut and mouth. Here are some key diet tips for better oral and gut health:

    • Eat fibre-rich foods: foods like fruits, vegetables, and whole grains help stimulate saliva production, which helps neutralise acids and wash away food particles.
    • Include lean proteins & healthy fats: these foods provide essential nutrients for immune health and help reduce inflammation in the mouth and body.
    • Cut back on sugar: sugar feeds harmful bacteria in both your gut and mouth. Try to limit sugary snacks and drinks to reduce the growth of these bacteria.
    • Stay hydrated: drinking plenty of water keeps your mouth moist, helping to wash away bacteria and food particles.
    • Limit processed foods: highly processed foods can disrupt the balance of your gut microbiome and lead to oral health issues.

    The bottom line

    Gut health and oral health are closely connected, and maintaining a balanced diet, rich in probiotics and nutrient-dense foods, can support both.

    By nourishing your gut with healthy foods, you can promote a healthy mouth, fight oral infections, and improve your overall well-being.

    Want to learn more about smile-friendly foods? Check out our best foods for teeth guide!