The Oral Microbiome: A Missing Piece in Whole-Body Health

Many of us have heard of the gut microbiome and the trillions of microorganisms like bacteria, fungus, and viruses that compose it. However, we often don’t think of other areas of our body that also house microorganisms, such as our skin, lungs, urinary and reproductive tracts, and our mouth [1]. The oral microbiome that resides in our mouth is the second largest microbiome in the human body and it has a huge impact on our overall health [1, 2].

Digestion begins with the cephalic phase, which is where sensory information such as sight, smell, thought, or taste triggers the release of saliva and gastric juices to prepare for food. Therefore, the mouth is the beginning of our digestive system and a gateway into our body. Functions that the mouth performs, like chewing, stimulate saliva production as well as properly break down food, increase nutrient absorption, and suppress hunger. Saliva contains various enzymes to help break down food, and it contains lysozymes, which are a key component of our immune system that protect against infection (natural antiseptic). The mouth’s tissues also contain a variety of immune cells like neutrophils, monocytes, and lymphocytes [1]. Hence, the mouth is also the beginning of our immune system.

The oral microbiome is a community of bacteria, fungi, and viruses that live in the mouth on our teeth, saliva, cheeks, soft and hard palates, tonsils, throat, lips, and tongue. Under healthy conditions, the good or commensal microorganisms keep the opportunistic or pathogenic microorganisms in check, just like in the gut microbiome. The microbes communicate with other cells to support health and prevent inflammation [1, 2]. The oral microbiome also helps in nitric oxide production by reducing dietary nitrites in food (beets, leafy greens, fruit, garlic, nuts). Nitric oxide is important in blood pressure regulation, circulation (blood flow, oxygen, and nutrient delivery), immune function, and brain health [3]. However, if the oral microbiome becomes dysbiotic (opportunistic microorganisms are left unchecked), it can affect the whole body, not just the mouth, and impact systemic inflammation and disease. This can occur through various routes, but the main routes include the oral-gut axis and the bloodstream [1, 2, 3, 4, 5]. 

The oral-gut axis provides a bidirectional pathway from our mouth to our gastrointestinal tract. Along the way, we have a variety of defenses to support the health of this pathway, including lysozymes in our saliva, stomach acid, bile, intestinal mucosa, and tight junctions. 

Research has shown that a healthy mouth protects against oral, brain, immune, metabolic, and gut health. Unfortunately, the prevalence of chronic inflammatory diseases is rising. In general, inflammation is the body’s natural immune response to heal and repair tissues subjected to injury, infection, or irritation. However, if inflammation isn’t able to resolve for months or years, then it can lead to long-term damage of healthy tissues and organs [1]. Studies show that oral dysbiosis and chronic inflammation have been linked to conditions such as dental cavities, periodontitis, atherosclerosis, heart disease, autoimmune conditions (rheumatoid arthritis, Lupus, inflammatory bowel disease), neurodegenerative conditions (dementia, Alzheimer's), respiratory diseases, metabolic disease (insulin resistance, diabetes, obesity), colorectal cancer, and gut dysbiosis [1, 2, 3, 4, 5].

Oral health isn’t cosmetic, it’s whole body health. Since the mouth is the beginning of our digestive and immune systems, it’s crucial to have good nutrition habits as well as good oral hygiene to support the health of the oral microbiome. Nutrition support includes focusing on whole, unprocessed foods that are rich in protein, healthy fat, and fiber to support blood sugar balance, feed good microbiota, and provide adequate nutrients, minerals, fat-soluble vitamins, and probiotics to support immune function and protective barriers in our oral-gut axis. Other lifestyle tips include quitting smoking, nervous system regulation, and mindful eating practices (smelling and admiring the sight of your food to stimulate saliva, chewing to applesauce consistency, etc.) [2].

Regarding oral hygiene, brushing and flossing daily, tongue scraping/brushing, using an oral irrigator (such as Proclaim), avoiding overuse of harsh antiseptics like mouth wash, and regular dental check-ups are helpful in maintaining a healthy mouth [2].