Canker sores, medically known as aphthous ulcers or aphthous stomatitis, are a common oral health concern that affects approximately 20% of the general population. While these painful lesions typically heal on their own within a couple of weeks, some individuals may experience recurrent or severe canker sores, which can significantly impact their quality of life. In this article, we will explore a functional medicine approach to diagnosing and treating canker sores, focusing on understanding their causes, the laboratory tests that functional medicine doctors commonly order, and integrative therapies that can be employed to alleviate symptoms and prevent recurrences.

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What Are Canker Sores?

Canker sores are small, round or oval-shaped ulcers that develop on the inside of the mouth, on the inner lips, cheeks, tongue, and sometimes even in the throat. They are characterized by their white or yellowish centers, surrounded by a red border, and are often painful or uncomfortable. They can vary in size, ranging from less than one millimeter to one inch in diameter. Unlike cold sores, which are caused by the herpes simplex virus and appear on the outside of the lips, canker sores are not contagious. (3) 

Canker sores can be broadly classified into three categories. Minor aphthous stomatitis, the most common type affecting more than 80% of canker sore sufferers, is characterized by sores less than one centimeter in diameter that heal within two weeks without scarring. Major aphthous stomatitis affects approximately 15% of people with canker sores. It presents with larger, deeper, and more painful ulcers, often 2-3 centimeters in diameter. They may have irregular, raised borders and can take months to heal, leaving scarring after the sore resolves. The least common form of ulcer is herpetiform recurrent aphthous stomatitis, which tends to occur as clusters of very small, painful lesions ranging from 1-2 millimeters in diameter that heal in just over one week. (2, 17)

What Are the Possible Causes of Canker Sores?

Anyone can develop canker sores, but they're most common in people assigned female at birth during adolescence and early adulthood (second and third decades of life). Ulcerations result from immune dysfunction and destruction of the oral mucosal epithelium. (17)

Minor oral trauma/injury, such as accidentally biting the inside of the cheek, aggressive tooth brushing, or dental work, can initiate the formation of canker sores (1). Emotional stress is also associated with the condition. A 2013 randomized control trial including 160 participants concluded that mental stressors are more strongly associated with oral ulcers than physical ones.

Dietary factors can play a role in developing aphthous stomatitis through various mechanisms. Acidic, spicy, and salty foods can irritate the oral mucosa lining, causing ulceration (3). Immune-mediated sensitivities and allergies have also been implicated, including those to sodium lauryl sulfate in oral hygiene products, cinnamon, cheese, chocolate, citrus, coffee, eggs, figs, nuts, pineapple, and strawberries (1, 17). Nutritional deficiencies, particularly in vitamin B12, iron, folate, and zinc, have also been linked to recurrent canker sores (10).

Menstruation gingivitis can occur in some women due to hormonal changes during the menstrual cycle. Symptoms include red swollen gums, bleeding gums, swollen salivary glands, and canker sores that appear 1-2 days before a period and resolve shortly after the period has started.

There is likely also a genetic component that predisposes certain individuals to developing canker sores. One study suggested that certain genetic polymorphisms of the IL-10 gene alter cytokine production and are linked to recurrent aphthous stomatitis (RAS). Additionally, more than 42% of patients with RAS have at least one first-degree relative with RAS, further supporting a genetic etiology. 

Mouth ulcers may be an early sign of autoimmune disease. A large, nationwide population-based cohort study sought to estimate the risk of developing autoimmune disease in patients diagnosed with RAS. They concluded that patients with RAS had an increased risk of developing Behcet's disease, systemic lupus erythematosus (SLE), ankylosing spondylitis, Hashimoto's thyroiditis, Graves' disease, and rheumatoid arthritis (RA). Canker sores are also a common symptom of celiac disease and Crohn's disease.

Functional Medicine Labs to Test for Root Cause of Canker Sores

Functional medicine approaches healthcare with a focus on identifying the underlying causes of health issues rather than merely treating symptoms. When diagnosing and managing canker sores, functional medicine doctors often employ a range of laboratory tests to investigate potential triggers and contributors. 

Micronutrients

Assessing levels of essential nutrients helps identify deficiencies that contribute to canker sores. Standard blood tests for nutrient deficiencies associated with canker sores include ferritin, serum vitamin B12 and folate, and RBC zinc. 

Food Sensitivities & Allergies

Identifying specific food sensitivities or allergies can be crucial, as dietary factors can play a significant role in canker sore development. Some people may opt to initiate an elimination-rechallenge diet, which involves removing suspected trigger foods from the diet for a period before reintroducing them to identify reactions. Testing can take out the guessing work in identifying food allergies and sensitivities and help to customize therapeutic diets. These tests measure IgE, IgA, and IgG antibodies in the blood, which indicate an abnormal immune response to food proteins.

Hormones

The Rhythm Plus panel by Genova Diagnostics is an example of a functional salivary test that measures sex and stress hormones over 28 days. This type of test better evaluates hormonal fluctuations throughout a menstrual cycle to identify imbalances that can easily be missed on a single blood test.

Immune Function

For those with suspected autoimmune conditions, ordering an autoimmune panel is the first step in diagnosis to detect relevant immune proteins associated with the diseases. Inflammatory markers CRP and ESR are also commonly elevated in active autoimmune disease and can provide insights into the inflammatory processes that may be linked to canker sores.

Additional Labs to Test 

Changes in the oral microbiota have been proven to increase the occurrence of oral ulcers. A functional dentist will commonly test the oral microbiome to detect dysbiosis contributing to immunological dysfunction and recurrent ulcer formation.

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Conventional Treatment for Canker Sores

While canker sores typically resolve on their own within a week or two, treatment options exist to help manage symptoms and expedite the healing process. Conventional treatment options for canker sores can be divided into four categories: antibiotic, anti-inflammatory, immunomodulating, and symptomatic. Topical and systemic tetracycline and minocycline antibiotic treatments are empirically used based on the belief that there is a yet-to-be-discovered infectious agent responsible for causing canker sores. Local anti-inflammatory agents like triamcinolone can speed healing and relieve symptoms. Immunomodulators have been investigated to manage severe aphthous ulcers in patients with HIV. Other agents, including topical lidocaine or oral nonsteroidal anti-inflammatory drugs, can manage pain. (12) 

An Integrative Medicine Approach to Treating Canker Sores

Once the potential underlying causes have been identified through functional medicine diagnostics, an integrative approach to treatment can be employed. This approach combines conventional medical care with complementary therapies to address the root causes of canker sores and relieve symptoms.

Nutritional Recommendations to Treat Canker Sores

Overall, the quality of evidence supporting dietary therapies in treating canker sores varies, and the effectiveness of nutritional interventions can be somewhat inconclusive. One study that included 754 Chinese participants aged 18-59 years concluded that eating a diet rich in fruits, vegetables, and dairy and drinking adequate amounts of water were protective against RAS. 

Understanding that adverse food reactions can cause canker sores, implementing an elimination diet may help reduce the frequency and severity of ulcer outbreaks. This would be particularly important for individuals diagnosed with celiac disease who require a strict, lifelong gluten-free diet for disease remission.

In cases of nutrient deficiencies, supplementation with certain vitamins and minerals, in addition to incorporating specific foods into the diet, may be recommended by a healthcare provider to correct the deficiency. 

Herbs and Supplements for Treating Canker Sores

Limited scientific evidence exists to support the use of natural remedies in treating aphthous ulcers; however, several agents have been used historically and reported anecdotally to provide local relief and speed up the healing time of ulcers.

A small study explored the potential use of zinc sulfate in treating or preventing recurrent oral ulcers. Serum zinc levels were measured in 32 patients with recurrent ulcers, and those with low levels (below 110 micrograms/dL) were given zinc sulfate supplementation (up to 660 mg/day). Patients with low initial zinc levels showed improvement with the intervention. Some, but not all, patients with normal zinc levels also experienced improvement. Patients who experienced improvements noted a reduction of ulcer outbreaks by 50-100%. (13) 

Studies reveal that vitamin B12, folate, and iron deficiencies occur in 20% of patients with recurrent aphthous ulcers. One study showed that of patients with a diagnosed nutritional deficiency, 59% experienced complete remission of ulcers, and 28% experienced improvement of symptoms when given appropriate supplementation.

Anti-inflammatory and healing herbs that have the potential to be effective in treating ulcers and supporting the integrity of the oral mucosa include licorice, chamomile, and aloe vera (18).   

Complementary Therapies for Canker Sores

Given the strong relationship between psychoemotional stress and RAS, it can be assumed that implementing stress-management therapies can help. Stress reduction techniques such as mindfulness meditation, yoga, and deep breathing exercises can effectively help to manage stress.

Improving oral hygiene practices and addressing dental issues can help prevent oral trauma and reduce the risk of canker sore development. Brush your teeth gently twice daily, using a soft brush and foaming-agent-free toothpaste, and floss once daily. (1, 3) 

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Summary

Canker sores can be a persistent and painful oral health issue for some individuals. A functional medicine approach to diagnosing and treating canker sores focuses on identifying and addressing the underlying causes rather than simply managing symptoms. By employing diagnostic laboratory tests, including nutritional, hormonal, and gut health assessments, functional medicine doctors can uncover the factors contributing to canker sores. Integrative therapies, such as dietary modifications, stress management, and oral care, can then be tailored to each individual to relieve symptoms and reduce the frequency of recurrences.