An imbalance in the oral microbiome, the bacteria living in our mouths, increases the risk of developing certain serious diseases, a researcher warns.
- An imbalance in the oral microbiome can lead to respiratory diseases such as pneumonia, but also to cardiovascular diseases, probably due to excess inflammation linked to the immune response.
- Some bacteria in the oral flora, such as Fusobacterium, which has “a high affinity for malignant tumor cells,” are also associated with colon cancer. Infected tumors are said to be more aggressive than uninfected ones.
- Studies have also shown that the brains of people with Alzheimer’s have been colonized by Porphyromonas gingivalis, one of the main bacteria that causes gum disease.
Just like the gut microbiome, the oral microbiome – the set of bacteria and other microorganisms living in our mouth – plays a vital role in our health. An imbalance in this oral flora, caused by poor diet or oral hygiene, can lead to infections, the most well-known of which are cavities or gum disease (gingivitis, periodontitis).
But that’s not all: an unbalanced oral microbiome can also lead to much more serious pathologies, far from the mouth. This is what Professor Gary Moran, from Trinity College Dublin (Ireland), reminds us in an article published in the independent media The Conversation.
Oral microbiome imbalance and respiratory diseases
“Given that the airway begins in the mouth and ends in the lungs, it is not surprising that an overgrowth of the oral microbiome could lead to inhalation of these microbes into the lungs.”writes the researcher. An excess of bacteria such as Streptococcus pneumoniae And Haemophilus influenzae can thus lead to respiratory diseases such as pneumonia or chronic obstructive pulmonary disease (COPD), characterized by shortness of breath, persistent cough or increased production of sputum.
An association between oral microbiome and heart disease
“Scientists have been intrigued for years by the strong association between gum disease and cardiovascular disease.”continues Gary Moran, specifying that this could be “linked to common risk factors”these two types of pathologies being for example more frequent among smokers.
Another explanation is that gum disease, like any infection, triggers a significant inflammatory immune response to fight it. However, too much inflammation in the body’s tissues can “damage the cardiovascular system.” Furthermore, pathogenic bacteria in the gums could “reach the heart and cause infections”but this remains to be proven.
One thing is for sure: studies show that treating gum disease helps reduce the level of inflammation in the bloodstream and boost arterial function, which limits heart risk.
Mouth bacteria and colorectal cancer
“Oral bacteria are known to travel through the stomach and into the intestines. Typically, they don’t adapt well to this new environment and eventually die off.”explains Professor Moran. But in 2014, two studies showed that bowel cancers were heavily colonized by a species of bacteria called Fusobacteriumwhich is usually found in dental plaque and has “a high affinity with malignant tumor cells.”
According to this work, patients with colorectal cancer who are largely colonized by this family of bacteria respond less well to chemotherapy and have a shorter life expectancy than others. And for good reason, tumors infected by Fusobacterium would be more aggressive than those that are not, and therefore likely to spread throughout the digestive tract.
Gum disease and Alzheimer’s disease
“Gum disease has been linked to greater cognitive decline in people with Alzheimer’s disease, assures Gary Moran. But because both diseases are linked to aging, it is difficult to determine whether there is a cause-and-effect relationship.” In 2019, however, researchers demonstrated that the brains of people suffering from Alzheimer’s have been colonized by Porphyromonas gingivalisone of the main bacteria that causes gum disease. But the idea that the brain, which is supposed to be sterile, could be infected by oral microbes remains “very controversial”, according to the specialist.
So many diseases linked to the oral microbiome that should encourage us to take great care of our oral hygiene, by brushing our teeth twice a day, flossing, going to the dentist or even avoiding smoking.
