The mouth-brain link: how healthy gums could help protect against Alzheimer’s disease

We all know we should clean our teeth daily, but good oral hygiene can do more for you than give you a healthy smile. According to experts, it could improve your brain health and reduce the risk of developing Alzheimer’s disease.

Poor dental care can lead to gum disease (gingivitis) when bacteria builds up around the teeth and gums, which can result in more severe and irreversible gum disease, known as periodontitis. These bacteria don’t always stay put—they can enter the bloodstream and trigger chronic inflammation, which is linked to brain aging and conditions like Alzheimer’s.

“Multiple large studies and scientific reviews now show a consistent link between gum disease and an increased risk of Alzheimer's disease and other forms of dementia,” says dentist and oral health expert Dr Kami Hoss, author of If Your Mouth Could Talk.

“A 2025 umbrella of reviews—covering 52 studies spanning two decades—suggests that people with gum disease are significantly more likely to develop Alzheimer’s than those with healthy gums.”

Hoss, who is also the founder of oral care brand SuperMouth, adds: “None of this surprises me. The mouth is not a separate system. It has never been. And science is finally catching up to what dentists have understood for a long time.”

How can bacteria in the mouth influence the brain?

“There are multiple pathways—the most direct route is through the bloodstream,” explains Hoss. “When gums are inflamed, the tissue lining becomes compromised and the bacteria from your mouth spill into your blood every time you brush, eat or even chew.”

This means the bacteria can travel to distant organs, including the brain.

“Oral pathogens [microorganisms that can cause disease in the body] may also migrate directly to the brain through your nose or gut,” explains Hoss. “When the balance of bacteria in your mouth is disrupted, it can alter your gut bacteria too, and through what researchers call the gut-brain axis, that gut disruption promotes inflammation in the brain.”

Hoss says bleeding gums are a sign of inflammation. “That inflamed tissue creates a gap in your mouth's protective barrier that allows bacteria and their toxic byproducts directly into your blood.

“Once in the bloodstream, the primary gum disease bacterium, Porphyromonas gingivalis, releases toxins that damage the brain’s protective shield—the ‘blood-brain barrier’.”

Once that barrier is weakened, harmful substances can reach the brain more easily, potentially triggering inflammation and changes linked to conditions like Alzheimer’s disease, he adds.

Hoss says the evidence that poor dental hygiene can affect brain health is compelling. “It’s strong enough that we can’t dismiss it. The risk of developing Alzheimer's disease has been reported to double within a decade following a diagnosis of gum disease. That statistic stops people cold in my lectures—and it should.”

He points to a 2019 study published in Science Advances that found evidence of Porphyromonas gingivalis—the primary bacterium behind chronic gum disease—in the brains of some Alzheimer's patients.

Hoss says: “They also identified toxic proteins produced by this bacterium called gingipains in those same brains. The levels of gingipains correlated directly with the hallmark damage seen in Alzheimer's disease.

“You are finding a gum disease bacterium living inside the brain of an Alzheimer's patient, and the more of it you find, the worse the neurological damage.”

He adds: “More recently, the National Institutes of Health funded a $2.8 million research project at the Dental College of Georgia specifically to understand exactly how these oral bacteria may be invading the brain. The scientific community is no longer treating this as a fringe theory. It is a serious and active field of investigation.”

How to improve your oral and brain health

So, what can you do other than regular brushing and flossing? Hoss shared four things we can all do to reduce the risks further.

1. Avoid ultra-processed foods, especially refined sugars

“Diet is one of the most powerful levers we have and most people dramatically underestimate it,” says Hoss. “Refined sugars and ultra-processed foods directly feed the bacteria that cause gum disease, while also driving the body-wide inflammation connected to cognitive decline. That is two harms for the price of one.”

Hoss offers up some good news: “On the positive side, diets rich in whole foods, healthy fats, fermented foods, and colorful vegetables support both a healthier oral microbiome and a healthier brain.

“Fiber-rich plant foods act as natural prebiotics, feeding the beneficial bacteria in both your mouth and gut. Leafy greens support nitric oxide production, which benefits blood vessel health in both the brain and the gum tissue. What feeds your gums tends to feed your brain. The overlap is not coincidental—it is biological.”

2. Exercise regularly

Yes, there’s yet another benefit to exercising. Hoss explains that it “reduces the inflammatory proteins circulating in your blood, improves blood flow to the brain, and supports a more resilient immune response in your gum tissue.” This means white blood cells can combat bacteria more effectively.

“The lifestyle patterns that damage your gums tend to damage your heart and brain simultaneously. And the lifestyle patterns that protect one tend to protect all three. That is not a coincidence–it is a shared biology.”

3. Try an after-meals mouth spray and/or xylitol sugar-free gum

Hoss suggests that sugar-free gum containing xylitol can help reduce the bacteria that most causes cavity and gum disease, it does this by stimulating saliva production and raising oral pH between meals.

“Saliva is your mouth's natural defense and repair system. Not all sugar-free gum is xylitol gum, so read the label,” says Hoss, who also thinks there’s another tool that deserves far more attention than it gets: a mouth spray designed for use after meals.

“Most people have no oral care option between brushing sessions, which means hours of acid exposure, bacterial activity, and pH imbalance going unchecked throughout the day,” he explains.

“A well-formulated mouth spray with no artificial ingredients, no alcohol, an alkaline pH, and prebiotic ingredients can quickly neutralize the acid environment after eating, support the beneficial bacterial community, and freshen breath without disrupting your microbiome the way that alcohol-based sprays and rinses do.”

4. Focus on good quality sleep and stress reduction

How stressed you are and your sleep quality can negatively impact gum health.

“Stress hormones like cortisol and catecholamines can directly alter the behavior and growth of gum disease bacteria, essentially making them more aggressive,” says Hoss. “When you are chronically stressed, your immune system is suppressed and the pathogens in your gums are receiving a biological signal to become more harmful.

“Sleep compounds this. Poor sleep raises systemic inflammation, weakens immunity and reduces salivary flow.

“Managing sleep quality and stress is not just about your mental health. It should genuinely be part of your oral health strategy.”

Ideal oral hygiene routine

Hoss shares the routine he thinks you should be following:

• Brush for two minutes twice a day with a sonic electric toothbrush with PBT bristles, a pressure sensor and a UV sanitizing hub—to ensure your brush head is not reintroducing bacteria into your mouth with every use.
• Angle your toothbrush towards the gumline where the most dangerous bacteria colonize.
• Floss daily to break up the bacterial film between teeth—where your brush can’t reach.
• Choose toothpaste, mouthwash and floss that contain prebiotic ingredients including inulin (plant-derived fiber) and xylitol (a natural sugar alcohol) that feed and support the good bacteria in your mouth.