As humans, our bodies are composed of trillions of cells. In fact, it is estimated that we have more bacterial cells in the body than human cells! You may be familiar with the term ‘gut microbiome’ which is a collection of trillions of organisms living in our digestive tract, but did you know we also have an oral microbiome? 

The digestive tract actually starts at the mouth and ends at the anus. The oral microbiome is a collection of microbes such as bacteria, fungi, viruses, and parasites that greatly impact our health. The gut is often referred to as the ‘second brain.” With this known and well-documented connection, we will explore the oral microbiome and how oral health can impact brain health.

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The Fundamentals of Oral Hygiene

The term ‘oral hygiene’ refers to the practice of keeping the mouth clean and disease-free. Our oral health is linked to our overall health and wellness in more ways than you may realize. Think of your oral health as the window to your overall health. The following diseases or conditions are linked to poor oral hygiene:

• Endocarditis, which is an infection of the heart chambers or valves.
• Cardiovascular disease such as blocked arteries or stroke.
• Pregnancy and birth complications such as premature birth and low birth weight.
• Pneumonia, which is an infection of the lungs.
• Alzheimer’s, which affects memory, thinking, and behavior.

Oral hygiene is part of preventative wellness, as the health of our mouth is closely linked to the health of our body as a whole. There are several key components to good oral hygiene, including:

• Brushing your teeth at least twice a day using fluoride toothpaste and a soft-bristled toothbrush.
• Cleaning between the teeth at least once daily by flossing.
• Brushing your tongue or using a tongue scraper once or twice daily. Your tongue is like a sponge that holds onto bacteria.
• Scheduling routine dental exams at least every 6 months.
• Avoid smoking and other tobacco products, as these are a leading cause of gum disease and oral cancer.

Understanding Brain Health

According to WHO, “Brain health is the state of brain functioning across cognitive, sensory, social-emotional, behavioral and motor domains, allowing a person to realize their full potential over the life course, irrespective of the presence or absence of disorders.” There are several factors that influence the health of our brain, including:

Genetics: Our genes influence the development and function of the brain, including how we move, think, feel, and behave.

Diet: What we fuel our body with matters. Studies show that a diet high in refined sugars leads to impaired brain function and worsening of mood disorders. The ‘Western Diet,’ which is high in processed and refined foods and sugars, has been compared with the ‘Mediterranean Diet,’ which is composed of vegetables, fruits, unprocessed grains, and fish and seafood and contains only modest amounts of lean meats and dairy. 

Studies show that the risk of depression is 25-35% lower in those eating more of a Mediterranean Diet. You are also less likely to develop Alzheimer’s on this type of diet vs a Western Diet.

Sleep: One of our basic physiological needs as human beings is sleep. Proper sleep, a minimum of 7 hours, has been proven to improve memory, regulate metabolism, and reduce mental fatigue. Consecutive sleep, not fragmented sleep, gives your brain the time to consolidate and store your memories.

Stress: Studies show that stress can affect how the brain functions and processes information.  Stress also promotes inflammation and can lead to other chronic conditions such as heart disease. There is also evidence that chronic stress may actually rewire the brain so that more complex thinking is hindered.

Exercise: Staying active can help you think, learn, and problem-solve, as well as improve memory and reduce anxiety or depression. It is recommended to obtain 150 minutes of physical activity each week, which can be broken down into segments such as five 30-minute sessions.

Emerging Research on Oral-Brain Health Connection

Neuropsychiatric disorders such as schizophrenia, bipolar disorder, major depressive disorder, and attention deficit hyperactivity disorder in the 21st century are on the rise, as is research around the cause behind this phenomenon. These disorders have been found to be connected to the gut microbiome, which communicates with and influences the brain through the gut-brain axis. 

The mouth is the beginning of the digestive system and is a primary entry point for all things (including harmful pathogens) to access the internal body. The presence of microbes in the mouth and their byproducts within the bloodstream and nervous system can have damaging effects on the brain by stimulating inflammation within the nervous system.

Stroke is a leading cause of disability and the number five cause of death in the United States. Studies have shown an increased risk of stroke in individuals with gum disease, missing teeth, poor brushing habits, and lack of regular dental care. 

A seven-year analysis assessing the correlation between oral health and brain health found that those with overall genetically poor oral health showed increased damage to the structure of the brain. Therefore, it was determined that poor oral health may cause significant declines in brain health.

Functional Medicine Labs to Assess Oral and Brain Health

If you or your functional medicine provider suspects there is an imbalance in the oral microbiome contributing to poor brain health, there are several labs that may be beneficial. Below is a description of labs your provider may choose to order:

Comprehensive Stool Test

Our gut microbiome is closely correlated with numerous diseases in the body. Imbalances in the gastrointestinal microbiome can contribute to a variety of chronic illnesses, including mental health and brain function. Oral microbes can translocate to the gut through the oral-gut axis. Given this, testing the gut is a key tool in getting to the root cause of the underlying disease.

The GI-MAP test by Diagnostic Solutions Lab is a comprehensive stool analysis ideal for patients with conditions such as brain fog, mood disorders, and mental health conditions. It uses quantitative polymerase chain reaction (qPCR) technology to evaluate gut pathogens, bacterial infections, yeast overgrowth, viruses, and parasites. It also includes key markers related to digestion, absorption, inflammation, and immune function.

DNA Smile

Evidence to support the link between periodontal disease and conditions such as cardiovascular disease, diabetes, certain cancers, and cognitive decline continues to grow. The DNA Smile test by dnalife is a genetic test designed to provide insights into oral health and predisposition for developing periodontal disease, tooth caries, and other systemic diseases. 

The test shows gene variations involved in areas including Innate immunity, inflammation and acquired immunity, and sweet-tooth predisposition. This test also comes with personalized diet, nutraceutical, lifestyle, and oral health recommendations to offset possible genetic weaknesses and optimize oral and systemic health outcomes.

Additional Tests 

Conditions such as chronically inflamed gums, poor root canals, improperly fitting crowns, fillings from unideal materials, and metal scans all affect your oral microbiome and, potentially, your overall wellness. Regular preventive dental care is key to maintaining both your oral health and your overall health. Check-ups with your dentist not only help prevent tooth decay, gum disease, and oral cancer but they also help you avoid other health conditions such as cognitive impairment.

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Lifestyle Factors and the Oral-Brain Health Connection 

Lifestyle factors have a significant impact on our oral health and, thereby, our overall wellness, including the health of our brain. A balanced diet with adequate nutrients is essential for a healthy mouth. The foods you choose and your overall eating habits are essential in preventing tooth decay and gingival disease. A balanced diet rich in essential nutrients, such as vitamins, minerals, antioxidants, and omega-3 fatty acids, supports brain health. These nutrients play a role in cognitive function, memory, and overall brain function.

Smoking and alcohol consumption both negatively impact our brain health and oral health. Cigarette smoking and alcohol use have a high concentration of chemicals that deteriorate gingival tissue and raise the risk of mouth cancer. Smoking is also a major risk factor for cognitive decline and dementia, including Alzheimer's disease. In addition, excessive and chronic alcohol use can lead to alcohol-related brain damage and cognitive impairment.

There are many daily habits that have been found to have a positive impact on the health of our brain. Exercise is a foundational habit that supports brain health by improving blood flow and the release of neuroprotective chemicals. Additional daily habits that support a healthy brain include:

• Eating a diet rich in omega-3 fatty acids found in fish and certain nuts is particularly beneficial for brain health.
• Staying mentally active by engaging in activities that challenge your brain, such as reading or puzzles.
• Managing stress.
• Prioritizing sleep and aiming for 7-9 hours of uninterrupted sleep.
• Maintaining social connections and activities.

There are also daily habits we can adopt to promote the health of the oral microbiome, including:

• Brushing your teeth twice daily.
• Flossing daily to remove plaque and food particles.
• Staying hydrated.
• Limiting sugary, processed foods.
• Regular dental exams.

Nutritional Recommendations For Oral and Brain Health

Nutrition plays an important role in supporting both oral and brain health. An anti-inflammatory diet such as the Mediterranean diet, which focuses on foods like vegetables, whole grains, and healthy fats, is good for your brain as it minimizes white and gray matter changes. 

Another frequently recommended diet is the MIND diet, a combination of the Mediterranean diet and the DASH diet, which was developed to lower blood pressure. The MIND diet focuses on foods with brain-boosting powers, like fish and berries, while eliminating foods like red meat, fried foods, sugar, and fast food. Decreasing pro-inflammatory and processed foods can boost your cognition and prevent conditions such as Alzheimer’s and dementia.

Diet is also an important factor in the health of our oral cavity. One of the foods found to have the greatest impact on the oral microbiome and the development of periodontal disease is simple carbohydrates. These contribute to systemic and oral pro-inflammatory conditions. Simple and refined carbohydrates are also a risk factor for dental caries and periodontal disease. In order to support a healthy oral microbiome, a balanced diet with adequate nutrients is essential.

Supplements & Herbs For Oral and Brain Health

Botanicals have a long history of being supportive to the body in many ways, including promoting healthy brain function. Neuroprotective herbs may be used for supporting brain health and preventing diseases such as Alzheimer's dementia. A few herbs to consider include:

Ashwagandha has been shown to decrease stress, enhance mood, and improve cognitive function. It also helps to sustain attention and short-term memory in healthy young adults.

Cat's Claw or Uncaria tomentosa is a natural plant extract that may be useful in brain aging and Alzheimer’s disease. It has been found to inhibit the accumulation of beta-amyloid protein containing “plaques” and “tangles” found in these patient populations.

Ginkgo biloba has been shown to have a neuroprotective benefit in preventing memory loss in neurodegenerative diseases.

Lions Mane or Hericium erinaceus supports the production of nerve growth factors through its bioactive compounds. It has shown improvement in cognition.

Turmeric or Curcuma Longa has well-documented anti-inflammatory properties. It is supportive of gut health and, thereby, brain health.

Herbal supplements can contribute to oral health in several ways, primarily through their natural compounds and properties that can promote healthy teeth, gums, and overall oral well-being. Here are some ways herbal supplements can benefit oral health:

Probiotics are supportive of the gut microbiome and, therefore, the oral microbiome. Probiotics can modulate bacteria, improve intestinal barrier function, and strengthen the immune system.

Prebiotics support the microbiome by promoting the growth and function of probiotic microorganisms. Once fermented by gut bacteria, these produce short-chain fatty acids, which are highly anti-inflammatory.

Zinc has been found to be beneficial in the treatment and prevention of plaque-related diseases such as periodontal diseases and dental caries.

Vitamin D deficiency can have an impact on oral health in many ways. It can contribute to tooth mineralization, caries, and periodontitis. 

Selenium deficiency has been found to result in increased oxidative stress inside the body tissues with implications in oral lesions like leukoplakia.

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Summary

Oral health and brain health are more interconnected than you might think. Research has shown that there is a potential bidirectional relationship between the two, meaning that the health of your mouth can influence your brain health and vice versa. Specific ways in which oral hygiene is related to brain health include the development of potential infection, systemic infection, and mental health conditions. 

Maintaining exceptional oral health through regular dental check-ups, proper oral hygiene practices, and a balanced diet can help reduce the risk of oral infections and gum disease. This, in turn, can potentially reduce the risk of systemic inflammation and its impact on brain health. In summary, taking care of your oral health is a crucial component of maintaining overall health, including brain health.