The oral microbiome is the second largest microbial community in our body. And our mouth is home to this microbiome, with trillions of microbes and over 700 unique species of bacteria living in the mouth – on the tongue, cheeks, teeth. The average person has between 100 and 200 unique species of oral bacteria.
When this community enters a state of dysbiosis, the number of pathogenic anaerobic and cariogenic species increases, which in turn leads to tooth decay and gum disease.
The relationship between the oral microbiome and oral diseases has been established for a long time, but recently we have begun to understand that the influence of the oral microbiome goes beyond the oral cavity and affects the overall health of an individual.
5 Ways Oral Bacteria Impact Your Overall Health
1. Cognitive impairment
One area of growing interest is the link between gum disease-causing bacteria and cognitive decline. There are studies that have been aimed at elucidating the links between periodontal disease (periodontitis), tooth loss and cognitive decline up to dementia. They have proven that poor oral health is associated with cognitive decline. Adults with more tooth loss were 1.48 times more likely to develop cognitive impairment and 1.28 times more likely to be diagnosed with dementia, even after controlling for other factors.
However, many studies to date only correlate the occurrence of poor oral health with cognitive decline. New technologies are providing a deeper understanding of the relationship between the two conditions, and research suggests that gum disease may contribute to the development and progression of Alzheimer's disease.
A growing body of evidence suggests that one oral pathogen, Porphyromonas gingivalis, may be a key link between oral health and cognitive health. P. gingivalis antigens have been found in the brains of patients diagnosed with Alzheimer's disease.
Gingipains, a group of toxins produced by P. gingivalis, have attracted the attention of researchers studying the relationship between oral health and cognitive decline. A landmark study has found a correlation between gingipain levels and beta/tau amyloid levels in the brains of Alzheimer's patients. The researchers also identified P. gingivalis in the brain and cerebrospinal fluid of Alzheimer's patients. Further studies have found gingipains in neurons in more than 90% of patients diagnosed with Alzheimer's disease.
The study suggests that P. gingivalis may migrate from the mouth into the bloodstream, eventually reaching the brain. Once there, P. gingivalis can produce gingipains, which are associated with increased levels of beta-amyloid and tau proteins, eventually leading to cognitive decline.
Statistics show that in addition to cognitive decline, oral pathogens are implicated in chronic diseases that include heart disease, diabetes, poor pregnancy outcomes, bowel disease, and cancer, especially colorectal cancer.
2. Heart disease
Patients with severe gum disease were 2.22 times more likely to develop cardiovascular disease compared to controls.
Other studies have reported finding several types of oral bacteria, such as Fusobacterium nucleatum, in the heart tissue of patients with atherosclerosis. This discovery suggests that the bacteria migrated from the mouth to the heart.
3. Adverse pregnancy outcomes
Mothers with periodontitis face a higher risk of adverse pregnancy outcomes, including low birth weight, preterm birth, and preeclampsia. Some studies have shown that certain types of oral microbiome, such as F. nucleatum, can colonize the placenta and affect pregnancy.
4. Cancer
A meta-analysis that examined the relationship between oral disease and cancer found a 14-20% increase in overall risk of gum disease-related cancer, adjusted for smoking, which is a major risk factor for both diseases.
Furthermore, recent studies suggest that the periodontal pathogen F. nucleatum is likely to contribute to tumor development in colorectal cancer. In very low concentrations, but F. nucleatum is usually found in the gut and is enriched in tumor biopsy. Therefore, patients with high levels of F. nucleatum in colon tissues face a worse prognosis.
F. nucleatum can influence the growth of colorectal cancer in many ways. First, it can trigger uncontrolled cell growth by over-activating cell signaling pathways. Second, it can block our immune system's ability to destroy tumors and cause resistance to life-saving chemotherapy.
5. Beneficial bacteria
When our microbiome is healthy, beneficial bacteria reduce the risk of heart disease and cognitive impairment.
Beneficial bacteria, including Lactobacillus reuteri, Neisseria mucosa, and Streptococcus sanguinis, aid digestion and protect us from infections. They also play a key role in keeping our heart and brain healthy by helping to produce nitric oxide, a key molecule in the body that is responsible for regulating blood pressure.
Nitric oxide helps to increase vasodilation – the expansion of blood vessels, which is necessary for lowering blood pressure, improving metabolic and cardiovascular regulation, and improving cognitive functions. These nitrate-reducing oral bacteria promote denitrification, which converts nitrates and nitrites from our diet into nitric oxide.
Conclusion
As more research emerges on the relationship between the oral microbiome and health, it highlights the importance of understanding this relationship and informing patients about the critical role that oral health and the microbiome play in overall health and well-being.