Why Healthy Digestion Begins in the Mouth

Today we’re more aware than ever that digestive health plays a huge role in overall health. The gut is connected to your digestion, metabolism, immune system, and even the brain. But the easiest way to detect illness may be through the mouth.

A young woman brushing her teeth
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Your mouth and gut have a close bond. Oral health can have a direct impact on your gut health and vice versa. Oral health problems can be linked to poor digestive absorption and immune response.

The very first signs of digestive diseases may also occur in your mouth. Inflammatory bowel diseases like Crohn’s disease and ulcerative colitis all may exhibit oral signs.

Bleeding Gums: The Canary in the Coal Mine

Try to think of the digestive system like a river. It flows in through the mouth and continues throughout your body until it reaches the other end.

Chronic digestive diseases can be very hard to treat. The intestines are located in the middle of the digestive tract, which is the most complex part of the system. The mouth-body link can help to pick up problems occurring in the gut before they progress into longstanding disease.

Gingivitis or bleeding gums may be one of the first signs of inflammation in your mouth. Essentially, bleeding gums are a sign that there is unrest further along in the digestive system.

The connection begins with your gut’s role in controlling the immune system. When the immune system is "hyperactive" or inflamed, it overreacts to its surroundings. Bleeding gums is one of the first signs of potential digestive disease processes. Let’s look at some of these oral signs and what they can tell us about your gut health.

Flat, Red Patches on the Gums and Inside of Cheeks

These painful lesions can be a sign of vitamin B12 deficiency. People who don’t eat enough vitamin B12 (only found in animal products), can lead to a deficiency. Inability to absorb vitamin B12 can also lead to a deficiency.

Several conditions can hinder the body’s ability to absorb vitamin B12, including atrophic gastritis, pernicious anemia, celiac disease, and Crohn’s disease. Gastrointestinal surgeries can also reduce the body’s ability to absorb B12.

Oral Candida

Candida infection is a sign of immune imbalance. In the mouth, it may be a sign of zinc deficiency due to poor digestive function. Oral candida is also linked to conditions that cause an imbalanced gut flora such as:

  • Antibiotic use
  • Excess consumption of sugar and sugar-containing products
  • Pregnancy
  • Diabetes mellitus
  • Immunosuppression
  • A red or swollen tongue

This is typically a sign of immune imbalance in the digestive system. Deficiency in folic acid and other B vitamins can also cause a swollen tongue.

Mouth Ulcers or Aphthous Ulcers

Mouth ulcers and red, inflamed gums can indicate digestive problems. They occur due to an immune imbalance in the gut.

White Pus-Filled Lesions

These lesions in the mouth are similar to those seen in Crohn’s disease in the colon.

Burning Mouth Syndrome

As the name suggests, this is the sensation of burning in the mouth. There may also be a loss of taste, dry mouth, and oral inflammation. This can suggest mineral and low vitamin levels. However, it may also be a side effect of medications such as anti-depressants.

Autoimmune Diseases

The autoimmune response begins in the digestive system. However, specific auto-immune conditions can present in the mouth. These oral signs may assist in the diagnosis of the condition. Autoimmune diseases can be caused by changes in the gut microbiome, the population of bacteria that reside within the gastrointestinal tract.

Lichen Planus

A chronic recurrent rash that is due to inflammation of the skin and mucous membranes. The rash is characterized by small, flat-topped, many-sided (polygonal) bumps that can grow together into rough, scaly plaques on the skin. There may also be a rash in the lining (mucous membranes) of the mouth or vagina. It will appear as a lacy white lesion on the inner cheeks and gums. It may also exist alongside skin rashes or burning sensations in the mouth.


Oral pemphigus (most commonly Vulgaris) is a group of skin blistering disorders. Autoimmune antibodies target skin cells, causing break down and blisters. The oral mucosa may be red, inflamed, and ulcerated. Oral pemphigus often presents alongside skin lesions.

Celiac Disease

Celiac disease is caused by an autoimmune response to gluten. It can cause mouth ulcers and also disrupt tooth formation. This results in discolored or poorly formed tooth enamel. Teeth may be brown and rough with defects that can increase the risk of tooth decay.

Rheumatoid Arthritis (RA)

A chronic autoimmune condition causing painful, swollen joints. The inflammatory proteins in RA and gum disease are alike. If you suffer from RA, you may be at higher risk of gum disease.

Sjogren’s Disease

Sjogren's syndrome is an immune reaction to mucous cells. It results in the breakdown of salivary glands, reducing saliva flow. This can cause dry mouth and increase the risk of tooth decay and tooth loss. It may also cause dry eyes, skin rashes, joint pain, and numbness or tingle in extremities.

Metabolic Conditions and Weight Gain

Type 2 diabetes: Poor blood sugar regulation reduces the healing ability of your mouth. People with type 2 diabetes have a higher risk of gum disease. The condition may present in its early stages with bleeding and inflamed gums. Both conditions are also related to a higher risk of a heart attack. It’s now understood that type 2 diabetes presents with a shift in gut microbes.  

Obesity: Obesity is linked to inflammation that seems to worsen gum disease. While no causal link has been established, weight gain can have an impact on oral health. Similarly, there is a typical type of gut microbes that relate to obesity.

Your Mouth Is the Key to Overall Health

The expanding knowledge of the role of the gut in systemic diseases is a frontier in preventative medicine. If you’re looking to maximize your gut health, it’s important to first look in the mouth. Dental diseases are the first sign of digestive imbalance.

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By Steven Lin, DDS
Steven Lin, DDS, is a dentist, TEDx speaker, health educator, and author.