Managing our mouth microbes; are they the gateway to the gut and our overall health?
When we talk about gut health, we often jump straight to those ever-important twisty tubes inside our tummies and the medley of microbes within, overlooking where the journey begins.
We asked Dr Maria Papavergos (@thelifestyledentist) to talk to us about the start line and our oral microbiome (a term used to describe the microbes in your mouth).
The oral microbiome is the gateway to our gut microbiome and an important precursor of overall health – say hello to the oral-gut-axis.
The gastrointestinal mucosa (gut lining) is an extension of the oral mucosa (the lining of your mouth) and the two are directly linked. There is emerging evidence that bacteria making up the oral microbiome contribute to the risk of developing IBD.
For example, a study looking at mice with Inflammatory Bowel Disease (IBD) showed that the bacteria making up the oral microbiome contribute to the risk of developing IBD (Kitamoto, Nagao-Kitamoto & Jiao 2020). There is also a small body of evidence displaying the same variation tendencies of oral bacteria and gut bacteria in patients with IBD from saliva sampling too (Xun, Zhang & Xu, 2018).
Furthermore, for those that suffer with IBD, prevalence of poor oral health and gum disease is higher (Papageorgiou, Hagner & Nogueira, 2017) and there are several signs of IBD that may manifest in the mouth (Lauritano, Boccalari & Di Stasio, 2019).
We know the gut responds to stress (more on that here), through an increase in the production of the hormone cortisol, but did you know this response links to the oral microbiome too?
Stress slows saliva flow, not only impairing digestion, but reducing the buffering capacity within our oral environment that helps maintain oral symbiosis (the happy, balanced relationship between our oral microbes and ourselves). This symbiosis is in delicate balance and small environmental changes, including reduced saliva, can drive disease-causing bacteria to thrive and inhibit the growth of beneficial species. This imbalance is called dysbiosis and is when dental disease (gum disease and dental decay) can develop.
Stress also impairs our immune system, affecting both gut and oral health by increasing susceptibility to both oral and systemic infections.
Dietary patterns that can negatively impact the gut microbes, can also disrupt the oral microbiome.
Regular spikes in our sugar intake over time can drive down the numbers of beneficial species of bacteria in our mouths and our guts, reducing microbiota diversity (Marsh, 2018). This is an example of how a small dietary change can drive the types of bacteria that thrive in our mouths, which increase our risk of dental disease.
It is this microbiota diversity that is critical to both gut health and oral health, so to help support diversity, we’ve got plenty of tips here.
There is established evidence that periodontal (gum) disease is an independent risk factor and appears alongside several chronic inflammatory diseases, including type II diabetes, cardiovascular disease, chronic kidney disease and rheumatoid arthritis (Chapple & Genco 2013). This means that your oral health has a direct impact on your overall health.
There is also recent evidence connecting oral health to complications of COVID-19 infections, suggesting an imbalanced oral microbiome could be implicated in the severity of COVID-19 infection outcomes (Sampson, Kamona & Sampson 2020). This is of course early research and more needs to be done, but an important indication of the potential impact of oral health.
Our oral microbiome, like our gut microbiome, is populated (or some may say, seeded) from birth. There is emerging evidence to suggest that the mode of birth delivery and early breastfeeding habits affect the development of the oral microbiome and may impact long term oral and overall health (Dzidic, Collado & Abrahamsson, 2018).
We need larger and longer trials to understand just how so. With a further established genetic link predisposing us to periodontal (gum) disease (Larsson, 2017), it may seem that much of our oral microbiome is out of our control. However, aside from the familiar importance of oral hygiene, we have an opportunity to proactively nurture our oral microbiome through diet and lifestyle.
The food we eat is not only nourishing us, but our oral microbes too. A diet that includes a variety of fresh fruit and vegetables, particularly those rich in alpha-lipoic acid and vitamin C, like leafy greens and broccoli, show a positive effect on our immune response that characterises periodontal disease (Milward, Chapple & Carter, 2013). Including plenty of omega-3 fatty acids, abundant in oily fish (think SMASH – salmon, mackerel, anchovies, sardines and herring), is also supportive for the oral microbiome. A nutrient-rich diet that is low in refined carbohydrates has a down-regulatory role on our inflammatory status and thus our gum disease status (Chapple, 2009) and is also protective in reducing our risk of oral cancer (Kapil, Singh & Bahadur, 2003).
It is important to be mindful of regular intakes of damaging extrinsic ‘free’ sugars and be able to identify them, since they are often hidden in foods we would not expect. Sugars found naturally in whole fruit and vegetables do not count as ‘free sugars’. They are known as intrinsic sugars. ‘Free’ sugars are sugars that are released from their protected intrinsic form through processing, eg. juicing. Choose whole fruit over juices and smoothies and remember ‘free sugars’ are also natural sugars, found in honey or maple syrup and added sugars, hidden in table sauces like tomato ketchup. Indulge knowingly and remember moderation is key!
Enjoying varied fruit and veg is not only good for gut health but is essential for oral health too. Plentiful in polyphenols and high in fibre too, we are promoting oral and gut microbiota diversity, whilst stimulating saliva flow through the chewing action these fibrous foods demand. Similarly, a diet low in refined carbohydrates is supportive for oral health since these foods can accumulate on your teeth, acting as a substrate for bad bacteria to cling onto and give rise to bad breath.
Consuming foods containing live bacteria, especially fermented dairy foods like kefir and natural yoghurt, may support beneficial oral bacteria and inhibit the production of volatile sulphur compounds (VSCs) in the mouth. VSCs are the smelly compounds produced by anaerobic bacteria in our mouths, so by banishing them away, we can keep bad breath at bay (Suzuki, Yoneda & Takeshita, 2019).
Stress is closely linked to gut health and oral health, so by adopting a healthy, active lifestyle that embraces some form of mindful exercise such as yoga, we can help to manage our stress levels. A lifestyle that allows plenty of reparative sleep will also help reduce stress and support our oral and gut microbiomes. More on that here.
Hydration is key to gut health but upping our fluid intake can also prevent dry mouth. Aim for around two litres of water per day, remembering this can include herbal teas, or hot water with added fresh mint or grated ginger. Ginger has been shown to have anti-inflammatory and anti-microbial properties against pathogenic oral bacteria too (Giriraju & Yunus, 2013).