I’ve written extensively about the power of our gut bugs for modulating our health and wellness. These little critters have been found to impact everything from our mood to cancer risk. However, with all the focus on our belly, many are forgetting that digestion begins in the mouth. Did you know that we have a wide array of critter residents there as well and some of them correlate to our belly bugs! Still, there is much to be learned about what lies in our oral cavity.
According to a 2013 article in Pharmacology Research:
The human mouth harbours one of the most diverse microbiomes in the human body, including viruses, fungi, protozoa, archaea and bacteria. The bacteria are responsible for the two commonest bacterial diseases of man: dental caries (tooth decay) and the periodontal (gum) diseases. Archaea are restricted to a small number of species of
methanogens while around 1000 bacterial species have been found, with representatives from the phyla Actinobacteria, Bacteroidetes, Firmicutes, Proteobacteria, Spirochaetes, Synergistetes and Tenericutes and the uncultured divisions GN02, SR1 and TM7. Around half of oral bacteria are as yet uncultured and culture-independent methods have been successfully used to comprehensively describe the oral bacterial community.
Our mouth microbiota can serve a helpful function. One small study reported that these little guys can help us with the production of nitric oxide. Cass Nelson Dooley, a respected researcher in the oral microbiome states, “Certain oral bacteria convert nitrate to nitrite from the leafy greens we eat in the diet. Humans cannot do this biochemical step so we rely on oral bacteria to help us make nitric oxide. Amazingly, these bacteria in the mouth may contribute up to 25% of systemic levels of nitric oxide. Veillonella and Actinomyces appear to have the strongest nitrate-reducing activity. Given the important
role of nitric oxide in healthy cardiovascular function and blood pressure regulation, we have to promote these bacteria by eating leafy greens and avoiding antibacterial mouthwash, when possible.”
The Bad Bugs in the Mouth
On the unhappy side, studies have connected some not-so-good mouth bacteria to various disease processes. These include a link to heart disease (especially endocarditis), respiratory infections, cancer, and even obesity.
According to a 2000 review:
Recently, it has been recognized that oral infection, especially periodontitis, may affect the course and pathogenesis of a number of systemic diseases, such as cardiovascular disease, bacterial pneumonia, diabetes mellitus, and low birth weight. The purpose of this review is to evaluate the current status of oral infections, especially periodontitis, as a causal factor for systemic diseases. Three mechanisms or pathways linking oral infections to secondary systemic effects have been proposed: (i) metastatic spread of infection from the oral cavity as a result of transient bacteremia, (ii) metastatic injury from the effects of circulating oral
microbial toxins, and (iii) metastatic inflammation caused by immunological injury induced by oral microorganisms. Periodontitis as a major oral infection may affect the host’s susceptibility to systemic disease in three ways: by shared risk factors; subgingival biofilms acting as reservoirs of gram-negative bacteria; and the periodontium acting as a reservoir of inflammatory mediators. Proposed evidence and mechanisms of the above odontogenic systemic diseases are given.
A recent article in Health Day reported that our mouth residents could also impact our brain:
In a new report, investigators reviewed studies on oral health and cognition published between 1993 and 2013. Some of the studies found that oral health indicators — such as the number of teeth, the number of cavities and the presence of gum disease — was associated with a higher risk of mental decline or dementia, while other studies did not find any association.
How to Have a Happy Mouth
What we eat has a huge impact on our whole body microbiome. Furthermore, smoking was just recently found to affect our mouth microbiome- could that be another reason why it is so bad for us?
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Cryan JF1, O’Mahony SM. The microbiome-gut-brain axis: from bowel to behavior. Neurogastroenterol Motil. 2011 Mar;23(3):187-92. doi: 10.1111/j.1365-2982.2010.01664.x.
Tillisch K, Labus J, Kilpatrick L, Zhiguo J, Stains J, Ebrat, B, et al. Consumption of Fermented Milk Product With Probiotic Modulates Brain Activity. Gastroenterology. 2013; 144 (7): 1394-1401.
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Gut microbes may play a role in colorectal cancer. MNT. March 4 2014. http://www.medicalnewstoday.com/articles/273472.php
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Nelson Dooley, C. The Mouth-Body Connection: Why We Shouldn’t Ignore the Oral Microbiome. Ask the Dentist. November 18, 2015. http://askthedentist.com/oral-microbiome/
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Preidt R. Is Seniors’ Dental Health Tied to Mental Health? Health Day. April 1, 2016. http://consumer.healthday.com/dental-and-oral-information-9/misc-dental-problem-news-174/could-dental-health-be-tied-to-mental-health-in-seniors-709520.html
Science Daily. How Bacteria Found in Mouth May Cause Colorectal Cancer. Sciencedaily.com. August 14, 2013.
Health Day. Smoking Triggers Big Changes in Mouth Bacteria, Study Finds. March 29, 2016. http://consumer.healthday.com/cancer-information-5/misc-tobacco-health-news-666/smoking-triggers-big-changes-in-mouth-bacteria-709469.html
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