The Gut-Oral Axis: How Gut Health and Oral Health Are Connected

To understand the connection between gut and oral health, it's important to be familiar with their microbiomes.

The oral microbiome hosts over 700 bacterial species living in different micro-environments, like tongue, hard palate, teeth, and areas around the gums. It's the second most diverse microbiome in our body and serves as the first meeting point between your immune system and the outside world.

The gut microbiome is a vast community of microorganisms in our digestive tract. To grasp its scale: a single drop of fluid from your colon contains more than a billion bacteria.

These two separate microbiomes communicate through the oral-gut microbiome axis, which allows both microbiomes to influence each other through the bloodstream, saliva, and the gut-brain axis.

How Poor Oral Health Affects Gut Health

The oral cavity is the starting point of the digestive system and a key regulator of microbial balance throughout the body. Disruptions to the oral microbiome—such as those caused by periodontitis or chronic inflammation—can contribute to systemic dysbiosis, particularly in the gut.

Oral-Gut Axis and Microbial Translocation

Saliva carries billions of oral microbes into the GI tract each day. In healthy individuals, most are neutralized by stomach acid and bile. However, in oral dysbiosis, pathogens are more likely to survive and reach the intestines, especially when gut integrity is compromised.

Periodontal Pathogens and Leaky Gut

Porphyromonas gingivalis, a harmful bacteria involved in gum disease, is especially tricky because it can survive harsh conditions like stomach acid. People with serious gum infections may swallow millions to billions of these bacteria every day. 

P. gingivalis can hurt the gut lining by weakening the proteins that keep it sealed tight. 

This makes the gut more "leaky," allowing unwanted substances to enter the bloodstream and trigger inflammation. Over time, this can contribute to health problems like inflammatory bowel disease, metabolic issues, and even brain disorders.

Inflammation and Autoimmune Conditions

When bacteria travel through the digestive tract or directly into the bloodstream, they can cause gut inflammation and potentially affect other body systems.

One of the earliest reactions following periodontal disease is gut microbiota dysbiosis. Research has linked this disease to several autoimmune conditions, such as rheumatoid arthritis, Systemic Lupus Erythematosus (SLE), and an increased risk of inflammatory bowel diseases.

Effects of Antibiotics

Dentists commonly prescribe antibiotics for dental infections and as prevention before certain procedures. While necessary, these antibiotics often don't distinguish between harmful and beneficial bacteria. When used in dental treatments, antibiotics can:

• Disrupt the delicate balance of beneficial gut bacteria

• Create an environment where opportunistic pathogens thrive

• Reduce microbial diversity in both oral and gut microbiomes

• Lead to antibiotic resistance with repeated use

Gum Disease and Immune Function

When the gut is inflamed, the immune system suffers, including your patient’s ability to fight off oral infections. 

A compromised immune response can make the gums more vulnerable to inflammation and periodontal disease, even when plaque levels are relatively low.

You might see signs like inflamed gums, recurring mouth sores, candida overgrowth, or a swollen tongue, often linked to nutrient deficiencies caused by poor gut absorption. 

Conditions like Crohn’s, celiac disease, or general dysbiosis can interfere with the uptake of essential vitamins and minerals that keep soft tissues healthy.

Tooth Erosion from GERD

Patients with acid reflux (GERD) often experience noticeable enamel erosion. 

When stomach acid enters the mouth, it creates a consistently acidic environment that wears down tooth surfaces, especially near the gumline and on the lingual surfaces. 

Over time, this can lead to sensitivity, increased risk of decay, and visible structural damage. GERD-related erosion is easy to miss if you're only thinking about diet-based acid exposure.

Bad Breath Linked to Gut Dysbiosis

Chronic bad breath isn’t always about poor oral hygiene. 

Gut imbalances—like small intestinal bacterial overgrowth (SIBO)—can produce gases that travel up and are released through the mouth. 

These volatile compounds often cause halitosis that doesn’t improve with brushing or flossing alone, pointing to an issue beyond the oral cavity.

Clinical Implications for Dental Professionals

Oral pathogens are not confined to the mouth; they may contribute to systemic disease through microbial translocation and chronic inflammation. 

Identifying at-risk patients—particularly those with GI or autoimmune disorders—and managing periodontal disease proactively can help reduce this systemic burden.

Advanced diagnostics, including AI-assisted detection, salivary biomarkers, and microbiome testing, make identifying oral dysbiosis easier. Incorporating these tools into clinical workflows supports a more integrative approach to patient care and systemic health.

The Role of Diet in Gut Health and Oral Health

What we eat impacts both systems, creating a reciprocal relationship where maintaining one positively influences the other.

Foods That Promote Health

Several food groups actively support both gut and oral health:

• Fiber-rich foods: Fresh vegetables and fruits help produce short-chain fatty acids (SCFAs), which reduce inflammatory responses in the gut. Foods like raw apples, carrots, dates, and sweet potatoes also help maintain oral hygiene by naturally removing plaque and food particles from teeth.

• Probiotic-rich foods contain beneficial bacteria that support gut microbiome diversity. The microorganisms in probiotics join good bacterial colonies, adding quantity and quality while crowding out harmful bacteria and balancing our gut microbiome. This balance positively affects oral health through the oral-gut axis.

• Nutrient-dense foods: Items rich in calcium, phosphorus, and vitamin C, such as dairy products, leafy greens, and citrus fruits, strengthen teeth and gums while supporting digestive health. Crunchy fruits and vegetables also promote saliva production, and help with oral cleaning.

Foods That Harm Health

Certain foods and beverages disrupt the delicate balance of both oral and gut microbiomes:

• High-sugar foods: When mouth bacteria feed on sugars from candies, sodas, and pastries, they produce acids that erode tooth enamel, causing cavities. These foods also disrupt gut bacteria balance, potentially leading to dysbiosis.

• Acidic foods and beverages: Soft drinks, fruit juices, wine, sports drinks, citrus fruits, and sour candies can erode tooth enamel over time. To minimize damage, avoid swishing these beverages in your mouth and wait at least 20 minutes after consumption before brushing your teeth.

• Sticky foods: Items like caramel and dried fruits can stick to teeth, increasing decay risk if not properly cleaned. These foods often contain high amounts of sugar, creating a double negative impact.

• Highly processed foods: Foods high in refined carbohydrates and low in fiber may promote inflammation throughout the body, contributing to gum disease and gut inflammation.

Additional Nutritional Considerations

Beyond specific food choices, several strategies can improve both gut health and oral health:

• Probiotic supplementation: Adding a spore probiotic supplement to your daily routine can significantly support oral and gut microbiomes. Certain strains of Lactobacillus and Bifidobacterium show particular benefit.

• Hydration: Proper hydration is essential for saliva production, which helps remove food particles, neutralize acids, and prevent dry mouth. Drinking enough water benefits both oral and digestive health.

• Exercise: Regular physical activity, particularly weightlifting, can boost SCFA levels for up to 18 hours while reducing inflammation.

• Intermittent fasting: This eating pattern has been clinically proven to decrease inflammation.

  
  

Actionable Tips for Dental Hygienists to Educate Patients

As a dental hygienist, you have a unique position to help patients understand the role of nutrition in gut health and oral health. Here are strategies to educate your patients:

Discuss the importance of fiber: Tell your patients that fiber isn't just good for digestion, it's excellent for teeth too. Fiber-rich foods help remove plaque and bacteria from tooth surfaces while feeding beneficial gut bacteria.

The same foods that create a healthy gut microbiome often support a healthy oral microbiome, which has a positive effect on overall health. Suggest specific high-fiber foods like fruits, vegetables, and whole grains that they can add to daily meals.

Highlight the benefits of omega-3 fatty acids: Share with patients that omega-3 fatty acids improve periodontal therapy outcomes when taken as supplements. These essential fatty acids reduce inflammatory responses throughout the body, including in the mouth and gut, and can promote beneficial gut bacteria growth.

Address sugar consumption directly: Be straightforward about sugar's impact on both oral and gut health. Explain how sugar creates an acidic mouth environment that promotes harmful bacteria while disrupting the gut microbiome.

Give practical advice for reducing sugar: read nutrition labels, choose water over sugary drinks, and satisfy sweet cravings with whole fruits instead of processed sweets.

Promote proper hydration: Remind patients that staying well-hydrated is important for saliva production, which naturally rinses away food particles and neutralizes harmful mouth acids. Suggest carrying a reusable water bottle and setting daily hydration goals.

Explain probiotics' potential: Discuss how certain probiotic strains might benefit oral health. Without exaggerated claims, mention that research from the National Center for Biotechnology Information suggests probiotics may enhance oral immune response and inhibit pathogens linked to periodontal disease. Advise patients to look for products with scientifically validated strains and proper dosages.

Advise on acidic foods and timing: Educate patients about erosive acidic foods and beverages. Recommend waiting at least 20 minutes after consuming acidic items before brushing their teeth. This allows saliva to naturally neutralize the oral environment and prevents enamel damage during brushing.

Create personalized nutrition plans: Offer to create simple, individualized nutrition plans supporting both oral and gut health based on patients' specific needs, preferences, and health conditions.

Contribute to The Oral Health of Your Community with Teero

Understanding the intricate relationship between gut health and oral health is important for dental professionals aiming to provide comprehensive care. By recognizing how these systems influence each other, dental hygienists can offer holistic guidance.

At Teero, we help dental hygienists take control of their careers, offering flexible scheduling and opportunities to work in diverse environments. Our user-friendly platform connects skilled professionals with dental offices in need for temporary or permanent positions.