The Oral Microbiome

This article summarises some on the research on the role our oral microbiome plays in both oral health, and most importantly our systemic health.

Microbes appear in every corner of human life, and microbes affect every aspect of human life (4).


The oral cavity is inhabited by a variety of microorganisms, their control aids in stabilising oral and systemic disease. The above image, summarises what conditions/organs/glands have been associated with the oral microbiome.

P Marsh (2018) explained it well by stating that “the oral microbiome is natural, and has a symbiotic relationship with the host (us) by delivering important benefits. In oral health, a dynamic balance is reached between the host, the environment, and the microbiome. However, the frequent intake of sugar and/or reductions in saliva flow results in extended periods of low pH, which disrupts this symbiotic relationship. Such conditions inhibit the growth of beneficial species and drive the selection of bacteria with an acid-producing/acid-tolerating phenotype, thereby increasing the risk of caries (dysbiosis).”

There is a very important point here – reduced saliva flow.

If you are a ‘mouth breather’ (a big clue being you wake up with a dry mouth) you are at greater risk of imbalances in the oral microbiome due to a lack of saliva flow. Saliva has a key role to play in regulating a healthy oral microbiome – it has anti-bacterial properties!

Significant evidence supports an association between periodontal pathogenic bacteria and preterm birth and preeclampsia (1).

Oral Microbiome & Cancers

The presence of elevated numbers of certain oral bacteria, particularly P. gingivalis, as well as elevated levels of blood serum antibodies, against this bacterial species, was associated with a higher risk of pancreatic cancer and liver cirrhosis incidence. Attempts are increasingly directed towards investigating the composition of oral microbiome as a simple diagnostic approach in multiple diseases, including pancreatic and liver pathosis (3).

Oral Health, Mastication & Cognitive Health

We also need to be mindful of how mastication and poor oral health can influence the ageing process, both directly and indirectly. Miquel et al (2018) discussed the current evidence and suggested that a deterioration in mastication and oral health during aging can have:

  1. Direct effects on systemic health through mechanisms such as the migration of the oral microbiota into the systemic environment (i.e oral bacteria in to the blood stream)
  2. Indirect effects on systemic health through changes in nutrient intake.

They went on to say that a loss of teeth and reduction in masticatory efficiency during aging can have:

  1. Direct effects on cognitive performance and potentially impact cognitive health through mechanisms such as enhanced adult hippocampal neurogenesis
  2. Indirect effects on cognitive health through changes in nutrient intake.

Miquel et al concluded that “oral health and masticatory efficiency are modifiable factors which influence the risk poor cognitive and systemic health during aging, although it is currently premature to propose chewing-based interventions to slow the rate of cognitive decline and improve cognitive health during aging” (2).


As Pete Williams discussed in episode 36 of The Alex Manos Podcast, we are more microbe than we are human. And thus to understand ourselves, to understand how we can support someone back to optimal health we need to understand their microbes. It seems, more now than ever before, that the oral microbiome is just as important as the gut microbiome. One paper summed it up well:

Studies in oral microbiomes and their interactions with microbiomes in variable body sites and variable health condition are critical in our cognition of our body and how to make effect on human health improvement (4).

Testing The Oral Microbiome

Invivo Diagnostics offer a oral microbiome test which is to be launched imminently (written July 2019).


  • Focus on the traditional oral hygiene practices – brush twice a day, floss daily. Consider the quality of your toothpaste. My two favourites are: Dentalcidin and Periobiotic.
  • Eat a diet rich in phytonutrients: plenty of fresh and ideally in season fruit and vegetables.
  • If you have periodontitis, or receding gums, consider eating 2-3 meals per day, with no snacking. Listen to episode 36 of The Alex Manos Podcast (see below) for further details on this recommendation. I would also recommend speaking with a qualified nutritional therapist/functional medicine practitioner before starting this however.


  • Episode 36 of The Alex Manos Podcast: click here, or search for it on your podcast platform (e.g iTunes).
  • The Dental Diet by Dr. Lin: click here.


  • Oral Dysbiosis in Pancreatic Cancer and Liver Cirrhosis: A Review of the Literature: click here.
  • A practical guide to the oral microbiome and its relation to health and disease.: click here.
  • The oral microbiome and human health: click here.
  • In Sickness and in Health-What Does the Oral Microbiome Mean to Us? An Ecological Perspective: click here.
Share this post