Everything You Need to Know About the Oral Microbiome

In 2019, nutritionist Megan Barnett, MS, CNS, met with a patient with puzzling lab results. Despite maintaining a consistent diet, exercise routine, and generally healthy lifestyle, the woman’s cholesterol levels had spiked significantly. While menopause can trigger higher cholesterol levels, that wasn’t the case here — the patient had been postmenopausal for more than a decade. Both she and Barnett were stumped.

Fifteen minutes after the appointment, the patient called Barnett from her car. Some­thing had occurred to her: Her dentist had recently discovered infections in the bone beneath five of her root canals. She wondered whether these hidden infections could drive her cholesterol levels up. Intrigued, Barnett decided to investigate.

In collaboration with the patient’s integrative dentist, Kelly Blodgett, DMD, NMD, IBDM, Barnett devised an experiment. They would run lab tests before and after their patient was scheduled to have the affected teeth removed.

The results were astonishing. Two weeks after the dental work, her cholesterol levels dropped 35 points, returning to optimal range.

“That really triggered my curiosity,” Barnett recalls. She started digging into the research. She learned that when the body encounters an infection, the immune response can lead to increased cholesterol production to support immune-cell function.

“We’ve always known that oral diseases affect cardiovascular health, but the question is, Why?” Barnett says. “One reason is because chronic inflammation in the mouth is triggering systemic inflammatory responses — not just in the heart, not just in the vascular system, not just in the mouth, but throughout the body.”

Since their initial discovery in 2019, Barnett and Blodgett have worked with dozens of patients. “We see consistently that there are huge improvements in overall health and well-being when we remove infections from the mouth and support the whole oral microbiome,” she says.

What Happens in Your Mouth

Second only to the gut, the mouth contains the most diverse microbial community in the body, featuring roughly 20 billion microbes from more than 700 species. Some of these microbes are beneficial; some are looking for trouble.

“About 5 percent of a healthy oral microbiome is made up of pathogenic organisms, with health-associated species making up the other 95 percent,” says Doug Thompson, DDS, founder of Wellness Dentistry Network, a community of dentists who take seriously the connection between oral conditions and whole-body health.

Thompson likens the bacterial communities in the mouth to the neighborhoods of a city. The teeth, tongue, cheeks, gums, and palate each have their own unique community of microbes. These microbes are active, absorbing nutrients and preventing infections, regulating pH levels in saliva, and influencing how quickly wounds heal.

Second only to the gut, the mouth contains the most diverse microbial community in the body, featuring roughly 20 billion microbes from more than 700 species.

The oral microbiome exchanges flora with the outside world as we breathe, eat, and drink, so these communities are constantly changing. This dynamism can sometimes lead to microbial imbalances known as dysbiosis.

“What happens with bacterial imbalance is the pathogenic load outpaces the healthy load, and up to 48 to 50 percent of the oral microbiome biomass is now pathogenic,” Thompson explains.

Signs of oral dysbiosis can include bad breath; swollen, bleeding, or receding gums; cavities and tooth decay; oral infections such as thrush; mouth sores; and increased sensitivity to hot or cold foods.

Several routes lead to dysbiosis, says Mark Malterud, DDS, MAGD. Risk factors include insufficient brushing and flossing; a diet high in sugar and ultraprocessed foods; antibiotics; tobacco use; dehydration; hormonal changes; types 1 and 2 diabetes; chronic stress; excessive alcohol consumption; and mouth breathing.

Oral Dysbiosis and Overall Health

When the balance of bacteria in the mouth is disrupted, it can lead to significant health issues in the mouth and beyond.

Inside the mouth, harmful bacteria, such as Porphyromonas gingivalis and Streptococcus mutans, form plaque on the teeth and along the gumline. This plaque is a type of biofilm, a stubborn microbial community protected by a slimy matrix. (Dentures and dental implants are especially susceptible to biofilms that can become problematic.)

The immune system responds with inflammation in the gums, known as gingivitis. If the plaque remains, tissue damage from inflammation allows pathogens to penetrate deeper into the gums, destroying connective tissues and bone. Eventually, gingivitis develops into periodontitis, in which the gums can pull away from the teeth, enabling pockets of infection to form.

Even after a dental cleaning, infected biofilm can grow back pathogenic and “often with more vengeance than it had before,” Malterud says. These treatment-resistant barriers require intensive and prolonged therapies.

According to the Centers for Disease Control and Prevention, roughly one in two men and one in three women in the United States have some level of periodontal disease.

“People blow off gum disease like it’s no big deal, but someone with full-blown periodontal disease basically has an open, infected wound equivalent in size to the palm of their hand. If you had a wound that size on your thigh, you’d take care of it real fast,” Malterud says.

Any kind of inflammation puts stress on the body, but chronic oral inflammation is especially problematic because it creates a persistent source of harmful bacteria with direct access to the digestive tract and, if the mouth contains open sores, the bloodstream.

Oral dysbiosis can also ­involve the presence of dangerous toxins that may damage blood-vessel linings, leading to increased risk of heart attack and stroke. The oral pathogen Fusobacterium nucleatum has been ­associated with preterm labor and low birth weight.

Dentists have now identified more than 57 diseases that are caused by or contribute to oral dysbiosis, Thompson says.

The Bigger Picture

These are some of the main aspects of health affected by the state of the oral microbiome.

1) Heart Health

Numerous studies highlight an association between oral bacteria and cardiovascular diseases. A study from the American Heart Association, published in 2021, found that people with gum disease have higher levels of LDL (“bad”) cholesterol in their blood than those with healthy gums.

Another recent study, in Postgraduate Medical Journal, shows exactly how oral dysbiosis damages arterial health. Researchers found that chemicals produced by high-risk oral bacteria can make the walls of the artery more permeable and vulnerable to the invasion of LDL cholesterol. These bacteria also produce substances that make the inner lining of the arterial wall stickier, so it’s more likely to trap bad cholesterol and generate plaque deposits.

Malterud often partners with a cardiovascular specialist who sends him heart patients with oral dysbiosis. “[My colleague’s] biggest thing is reducing oral inflammation and problems like chronic infections following root canals that fail to heal, because he’s concerned about how oral inflammation can set up cardiovascular disease, coronary artery disease, and cerebral vascular disease,” he says.

Studies indicate that tracking oral health can be especially important for anyone whose genetic predisposition puts them at greater risk for cardiovascular events.

2) Metabolic Health

Research indicates a bidirectional relationship between periodontal disease and diabetes. Oral inflammation caused by dysbiosis can worsen insulin resistance, and both types 1 and 2 diabetes can exacerbate periodontal disease, creating a vicious cycle.

“Bacteria love sugar, and they love unregulated sugar in the blood,” Thompson says.

A Cochrane Review published in 2022 found ­moderate-certainty evidence that periodontal treatment improves glycemic control “by a clinically significant amount” in people with both periodontitis and diabetes. 

3) Cognitive Health

Anything that damages the cardiovascular system is bad news for the brain, so it’s not surprising that the risks posed by oral dysbiosis extend to cognitive health. An increasing body of evidence points to chronic inflammation and microbial dysbiosis as risk factors for Alzheimer’s. Studies typically connect oral inflammation to the systemic inflammation involved in neurodegeneration and dementia.

Malterud points to new research suggesting a possible connection between oral pathogens and Parkinson’s disease. In a small study, researchers found that early- to mid-stage Parkinson’s patients had higher levels of oral inflammation than healthy controls, even though the groups had similar amounts of plaque.

A few microbes, includ­ing S. mutans, were more abundant in the mouths of Parkinson’s patients. S. ­mutans is linked to the formation of amyloid plaques, which can contribute to cerebral inflammation. 

4) Immune Function

The oral microbiome plays a crucial role in regulating the immune system. Healthy oral bacteria help maintain immune homeostasis; dysbiosis can lead to chronic inflammation and immune dysregulation. This can increase the body’s susceptibility to infections and other immune-related conditions, including autoimmunity.

Research has also indicated that disruptions in the oral microbiome can contribute to the development of allergic reactions, including asthma and peanut allergies.

Studies have shown that certain oral pathogens associated with joint inflammation are more prevalent in patients with rheumatoid arthritis. Other research suggests periodontal disease may increase the odds of a longer, more severe ­COVID-19 infection, mainly by promoting viral adherence and persistence in the mouth.

Research has also indicated that disruptions in the oral microbiome can contribute to the development of allergic reactions, including asthma and peanut allergies.

5) Cancer Resistance

Oral dysbiosis has been correlated with a range of gastrointestinal (GI) cancers, including those of the mouth, esophagus, stomach, colon, and pancreas.

In a study published in ­Nature in 2024, researchers examined F. nucleatum, one of the bacteria implicated in gum disease. The mouth normally contains small amounts of this bacterium, but in an imbalanced oral microbiome it can overgrow and trigger inflammation. The study noted that F. nucleatum is rarely found in the guts of healthy people, but it has been identified in some colorectal cancer tumors, suggesting it may travel from the mouth through the digestive tract and contribute to tumor formation.

F. nucleatum is rarely found in the guts of healthy people, but it has been identified in some colorectal cancer tumors, suggesting it may travel from the mouth through the digestive tract and contribute to tumor formation.

Barnett notes the oral pathogen P. gingivalis can survive the highly acidic environment of the stomach and migrate to the colon, causing a variety of digestive disorders. It has also been linked to GI cancers.

Because chronic inflammation is a risk factor for all cancers, oral inflammation may increase the risk of non-GI cancers as well. Studies have indicated associations between periodontal disease and an increased risk of lung cancer. A research team at Imperial College of London found that a history of gum disease increased the risk of kidney cancer by 49 percent and blood cancers, such as leukemia, by 30 percent in male subjects.

The burden oral dysbiosis puts on the immune system means oral health is particularly important for those undergoing cancer treatment, Malterud says. “When someone is going through cancer therapy, one of the best things they can do is stay on top of their oral health.” (The health of the body’s internal ecosystem can determine how well the body resists cancer, both before and after a diagnosis. Learn more at “What Is the Terrain Theory of Cancer?“)

Oral-Systemic Dentistry

Historically, Western medicine has treated the mouth as if it were separate from the rest of the body. “As dentists, we’ve always been looked on as the ugly stepchild of medicine,” Malterud says. But that is starting to change.

“I think there’s a huge groundswell that’s occurring within the dental community, and people are starting to understand that we as dentists are a gateway to overall systemic health,” he adds.

In 2022, the American Dental Association made it official policy to support and encourage collaboration and treatment discussions between dentists and their patients’ primary healthcare providers. A growing number of dentists now use tools to evaluate and treat the oral microbiome to help mitigate a range of issues, in the mouth and beyond.

“There are now more than 10 salivary diagnostic companies that I can order tests from, and they measure from five to 29 different pathogens that are most commonly associated with oral disease,” Thompson says.

As with gut-microbiome testing, there’s still much to learn about how specific microbes correlate to specific conditions, he adds. “We’re still gaining understanding about what the pathogens all mean and how they interplay with each other. That’s going to be unraveling for years to come.”

As the knowledge continues to develop, integrative dentists have gained access to a range of insights and tools to help restore balance to a disrupted oral microbiome. These also help to support overall health.

“Sometimes the first step is having teeth removed to resolve an infection site,” says Barnett. “But sometimes we need to look at all the other inflammatory factors that may be going on, as well as [a patient’s] nutritional status, to get them into a healthy-enough condition to respond well to a dental procedure.”

Other techniques include using a hydrogen peroxide solution under the gum line to kill harmful microbes in periodontal pockets that toothbrushes and floss can’t reach. Some dentists are treating patients who have dysbiosis with prescription antibiotics or herbal antimicrobials, depending on the severity of the condition. They’re also using ozone therapy, which targets anaerobic bacteria with concentrated oxygen, to eradicate pathogens.

The Care and Feeding of Your Oral Microbiome

Brush your teeth.

“A toothbrush is one of the best tools people can use,” says Malterud. Regular brushing — two or three times a day — helps remove plaque and food particles to prevent the growth of harmful bacteria.

Use a soft-bristled brush, which is easier on the gums, and take your time, spending at least two minutes scouring all the surfaces of the teeth from every angle. Using an electric toothbrush with a built-in timer can help ensure you brush for the recommended duration, or just set a timer on your phone. Be sure to replace the head of your toothbrush every three to four months; sooner if the bristles are worn down.

Toothpaste helps prevent oral dysbiosis but doesn’t treat it, Thompson says. “There are no toothpastes on the market with enough antimicrobial properties to correct dysbiosis.” He recommends seeking brands that include nano-hydroxyapatite, an ingredient that can help remineralize teeth, reduce sensitivity, and create an environment less favorable to pathogens.

He also recommends sticking with fluoride toothpaste if you are cavity-prone. “I don’t know of a better anticavity strategy than the topical application of fluoride. We just don’t want to ingest it,” he says.

Steer clear of toothpastes that use sodium lauryl sulfate (SLS), which can irritate tissues in the mouth and disrupt beneficial bacteria. (Visit “How to Avoid Toxins in Your Toothpaste: 12 Ingredients to Ditch Now.”)

 

Be sure to floss — and try a water flosser.

Regular flossing helps prevent gum disease by cleaning between teeth and below the gumline, where a toothbrush can’t reach. Yet even flossing may leave nooks and crannies where microbes can grow, Malterud says.

“A tooth is not perfectly round,” he points out. Tooth surfaces are uneven, particularly on the molars, so stretching a piece of floss around them inevitably leaves some divots untouched.

As a solution, many dentists recommend using a water flosser, which projects water at high pressure. It’s a bit like a power washer for teeth. “It does some mechanical removal of the biofilm as well as just flushing and liquid removal,” Thompson says.

To prevent or treat mild dysbiosis, he recommends adding a few drops of grapefruit-seed extract or powdered xylitol to the water-flosser reservoir to help prevent and remove biofilms.

 

Avoid commercial mouthwash.

Decades of TV commercials have promoted neon-colored, alcohol-based mouthwashes as the key to fresh breath. Unfortunately, these medicine-cabinet mainstays can do more harm than good. “Commercial mouthwash is detrimental to the oral microbiome,” Barnett says.

Strong antimicrobial agents are the selling point of many commercial mouthwashes, but these agents kill a full range of bacteria, including the beneficial ones that keep rogue bugs in check. This sets up the mouth for an overgrowth of opportunistic pathogens that resist anti-microbial treatments.

Some mouthwashes also alter the pH level in the mouth. “Commercial rinses can be very acidic, and our bad-acting biofilm loves to have an acidic environment to grow in,” Thompson says. He adds that acid itself damages the teeth. (This is also a reason to avoid carbonated sodas, which are highly acidic.)

People with a healthy oral microbiome shouldn’t need to use mouth rinses at all, Thompson says. ­Barnett adds that those trying to correct dysbiosis may benefit from a saltwater rinse or products made by Biocidin Botanicals, which contain herbs that promote a healthy microbial balance.

 

Eat a nutrient-dense, whole-foods diet — and stay hydrated.

Unsurprisingly, whatever you feed yourself, you’re also feeding your oral microbes.

When working with a patient to correct oral dysbiosis, Barnett focuses exclusively on supporting their oral microbiome with diet for the first 90 days. This entails adding fermented foods to increase microbial diversity; removing refined grains and sugar, which preferentially feed opportunistic bacteria; and cutting out alcohol.

“Then we give them a huge variety of plants, ­because those phytonutrients are going to support healthy microbes,” she explains. “We know now that it’s not just fibers and resistant starches that feed healthy microbes; it’s also the polyphenols.”

Omega-3 fatty acids act as food for healthy bacteria; probiotics can be helpful too. “Microbes are talking to each other all over the body, so addressing microbes in one area of the GI tract is going to affect the others,” Barnett adds.

Once the oral micro­biome is restored to health, eat a well-rounded, whole-foods, low-sugar, Mediterranean-type or other plant-forward diet to maintain it, Barnett advises.

It’s also important to drink plenty of water. Staying well hydrated promotes saliva production, which nurtures a healthy balance of bacteria in the mouth. (Try one of these three creative ways to boost your body’s hydration levels.)

 

Prioritize healthy sleep and nose breathing.

People with sleep apnea often breathe through their mouths, ­especially during sleep, which dries out the mouth. Because saliva helps neutralize acids and inhibit bacterial growth, a dry mouth is more conducive to harmful bacteria.

Chronic inflammation caused by poor sleep and ­reduced oxygen levels can also exacerbate gum inflammation and periodontal disease. “If you’re getting poor sleep, if you’re mouth breathing, if you’re not oxygenating, and you’re apneic, then we have to solve for that to protect your mouth,” Barnett says.

Because saliva helps neutralize acids and inhibit bacterial growth, a dry mouth is more conducive to harmful bacteria.

Though research on the efficacy of mouth taping is limited, some experts recommend the practice to prevent mouth breathing at night. It involves placing a small piece of mouth tape at the center of the lips. You can also try nasal strips across the bridge of the nose to help open nasal passages.

Nasal breathing not only fosters a better environment for healthy oral bacteria but also supports the production of nitric oxide. This improves blood oxygenation, supports immune function, and helps regulate blood pressure.

The mouth stands sentry at the gateway to the body, so by prioritizing oral health, we safeguard the entire body’s well-being. Doing this can also prevent poten­tial health issues before they start.

If You’re Afraid of the Dentist …

A lot of us avoid the dentist — or want to. According to the Cleveland Clinic, about 36 percent of Americans have a fear of dental treatment, with 12 percent having an extreme fear.

Finding a dentist who understands fear is ­crucial. Look for a practitioner who advertises a gentle, minimally invasive approach or specializes in treating anxious patients. Reading online reviews can also help identify compassion­ate providers.

“Minimally invasive dentists often take a more ­holistic approach to treatment. We take a little more time and get to know the patient,” says Mark Malterud, DDS, MAGD. “That’s the best way to get rid of a phobia. The patient has to feel [heard] and be given some level of control in the situation. Once they start relaxing, the dentistry gets a lot easier.”

These steps can help you overcome your anxiety.

1. Ask for help. Have a trusted friend or family member schedule the appointment for you.
2. Bring a friend. Taking someone with you can provide emotional support and distraction.
3. Practice relaxation techniques. Techniques like tapping (EFT) and eye movement desensitization and reprocessing (EMDR) can reduce anxiety before and during the visit.
4. Communicate your fears. Let your dentist know about your anxiety so they can ­adjust their approach to make you more comfortable.

The post Everything You Need to Know About the Oral Microbiome appeared first on Experience Life.