Does a lack of B-12 cause canker sores? Exploring the Nutritional Link

October 9, 2025 •

5 min read

According to research published in the Journal of the American Board of Family Medicine, patients with recurrent canker sores who were treated with vitamin B12 experienced a significant reduction in the duration and number of ulcers. This suggests a strong connection, affirming that a lack of B-12 can indeed cause canker sores in some individuals.

Quick Summary

A B-12 deficiency can contribute to or trigger canker sores, also known as recurrent aphthous stomatitis. The vitamin is vital for tissue health, and low levels may weaken the oral mucosa. While not the only cause, replenishing B-12 can help reduce outbreaks.

Key Points

B-12 and Oral Tissue: A lack of vitamin B-12 can weaken the delicate, fast-regenerating tissues of the mouth, making them more susceptible to canker sore formation.
Oral Symptoms as Early Warning: Painful oral symptoms like canker sores, glossitis, and a sore tongue can be early indicators of a systemic B-12 deficiency before other symptoms appear.
Supplementation May Be Effective: Studies suggest that B-12 supplementation can reduce the duration and number of canker sore outbreaks, even in individuals with normal B-12 levels.
Beyond B-12: Other nutritional deficiencies (iron, folate, zinc) and factors like stress, trauma, and certain foods also trigger canker sores.
Diagnosis is Key: Consulting a healthcare provider for a proper diagnosis is essential to determine if a B-12 deficiency or other issue is the cause of your recurrent canker sores.
Dietary Strategy: Increase B-12 intake by consuming animal products like meat and dairy, or fortified foods and supplements for those on plant-based diets.
Treatment Variety: Approaches may range from dietary changes and oral supplements to injections for severe cases, and topical ointments for localized pain relief.

The Connection Between Vitamin B-12 and Canker Sores

While the precise cause of canker sores, or recurrent aphthous stomatitis (RAS), remains a mystery, multiple studies have established a significant link between B-12 deficiency and the occurrence of these painful oral ulcers. Vitamin B-12 is a water-soluble vitamin essential for numerous bodily functions, including DNA synthesis and the formation of red blood cells. The delicate, fast-regenerating tissues that line the mouth are particularly vulnerable when B-12 levels are low.

One of the most notable oral signs of a B-12 deficiency is glossitis, a condition where the tongue becomes inflamed, swollen, and takes on an unusually smooth, red, and glossy appearance. This happens because low B-12 levels disrupt the production of healthy red blood cells, which are responsible for carrying oxygen to tissues throughout the body, including the tongue and oral mucosa. Without proper oxygenation, the oral tissues become weakened and more susceptible to developing sores.

Beyond direct tissue impact, some evidence suggests B-12 deficiency may affect the immune system's function, leading to a local immune response that contributes to the breakdown of oral mucosa and ulcer formation. In individuals with low B-12, the oral environment may be less resilient, allowing minor injuries or other triggers to escalate into full-blown canker sores.

Other Potential Triggers for Recurrent Aphthous Stomatitis

While a B-12 deficiency is a prominent factor, it is rarely the sole cause of canker sores. Many other elements can trigger or contribute to outbreaks, which is why a holistic approach to identification and management is crucial. A comprehensive evaluation by a healthcare professional is often necessary to pinpoint the specific triggers for an individual.

Key triggers include:

Nutritional Deficiencies: In addition to B-12, a lack of other key nutrients like iron, zinc, and folate can also trigger canker sores.
Minor Oral Trauma: Accidental cheek bites, overzealous brushing, dental work, or irritation from braces can cause initial tissue damage that develops into a sore.
Emotional Stress: Periods of high emotional stress, such as during exams, are frequently associated with canker sore flare-ups.
Food Sensitivities: Certain foods, including chocolate, coffee, cheese, nuts, and acidic or spicy items, can trigger ulcers in sensitive individuals.
Toothpaste Ingredients: Some people react negatively to ingredients like sodium lauryl sulfate (SLS), a common foaming agent in toothpastes.
Hormonal Changes: Many women notice a link between their menstrual cycle and the appearance of canker sores.
Systemic Diseases: Underlying medical conditions like Crohn's disease, celiac disease, or autoimmune disorders can manifest with oral ulcers.

B-12 Supplementation as a Potential Treatment

For those with recurrent canker sores, B-12 supplementation has shown promising results. Studies have indicated that B-12 treatment can significantly reduce the number, duration, and pain level of ulcers, even in people without a diagnosed deficiency. The sublingual (under the tongue) route is sometimes suggested as it may bypass potential absorption issues in the gut.

Potential Effectiveness of B-12 Approaches


Approach	Mechanism	Potential Timeline to See Results	Effectiveness Mentioned in Studies	Potential Benefit	Potential Drawback
Sublingual Supplementation	May be absorbed directly under the tongue, potentially bypassing the digestive system for entry into the bloodstream.	Studies have shown significant reduction in outbreaks after several months of consistent use.	Some studies indicate high effectiveness, even with normal initial B-12 levels.	Can be a simple, low-risk, and accessible approach.	May require consistent, long-term use for best results.
B-12 Injections	Intramuscular injection, delivering B-12 directly into the muscle tissue.	May take weeks to months, depending on the individual and severity of deficiency.	Highly effective, particularly for severe deficiencies or absorption issues.	Guaranteed absorption, may lead to rapid normalization of B-12 levels in some cases.	Requires a prescription and administration by a healthcare provider.
B-12 Ointment	Topical application directly to the ulcer.	May offer pain relief within a few days to a week.	Effective for localized pain and potentially aiding healing.	Fast-acting pain reduction at the site of the sore.	Generally does not address the underlying cause of recurrent ulcers.
Dietary Changes	Increasing B-12 rich foods to address nutritional gaps.	Variable, depends on severity of deficiency and dietary consistency.	May be less effective for treating existing severe deficiencies, but helpful for prevention and maintenance.	A natural and sustainable way to maintain B-12 levels over time.	May not be sufficient for individuals with underlying absorption problems.

Dietary Sources of Vitamin B-12

For those seeking to increase their B-12 intake through diet, focusing on animal products and fortified foods is essential, as B-12 is not naturally found in most plant-based foods.

Meat and Poultry: Beef, lamb, and chicken are sources of B-12.
Seafood: Clams, sardines, tuna, and salmon are among the sources. Just a small serving of clams can provide a notable amount of B-12.
Dairy Products: Milk, yogurt, and cheese all contribute to B-12 intake. The vitamin B-12 in dairy products is absorbed well by the body.
Eggs: Whole eggs are a source of B-12, with the yolk containing higher levels than the white.
Fortified Foods: For vegetarians and vegans, fortified breakfast cereals, plant-based milk alternatives, and nutritional yeast are potential sources of B-12. Always check food labels for fortification information.

Conclusion: Prioritizing Your Nutritional Health

While canker sores are often attributed to stress or minor trauma, a significant body of evidence shows that a lack of B-12 can indeed be a contributing factor, especially in cases of recurrent aphthous stomatitis. B-12 is crucial for maintaining the health of your oral tissues, and deficiency can leave the mouth vulnerable to inflammation and ulceration. Addressing a B-12 deficiency, whether through dietary changes or supplementation, can be a potentially effective strategy for reducing the frequency and severity of canker sore outbreaks. Given that a definitive cure for canker sores has not been found, nutritional management offers a simple, low-risk, and accessible approach to improving oral health and overall well-being. If you suffer from frequent canker sores, it is worth consulting a healthcare provider to have your B-12 levels checked, as early intervention can make a significant difference. You can find more comprehensive information on the topic by reviewing the available literature on recurrent aphthous stomatitis and nutritional deficiencies.

Disclaimer: This information is for general knowledge and should not be taken as medical advice. Consult with a healthcare professional before making any decisions related to your health or treatment.

Frequently Asked Questions

No, a B-12 deficiency is not the sole cause of canker sores and doesn't affect everyone in the same way. However, it is a significant risk factor, and studies show that low B-12 levels are a common trigger for recurrent ulcers.

A B-12 deficiency can disrupt the production of red blood cells, which carry oxygen to tissues. This leads to weakened, poorly oxygenated oral tissues that are more prone to inflammation and ulceration from minor irritations.

B-12 is naturally found in animal products like meat, fish, dairy, and eggs. Vegetarians and vegans can get it from fortified foods such as breakfast cereals, nutritional yeast, and plant-based milks, or by taking supplements.

While B-12 supplementation can significantly reduce the frequency, duration, and pain of recurrent canker sore outbreaks, especially when taken consistently over several months, it is not considered a permanent cure. Canker sores can have multiple triggers that may require ongoing management.

According to research, a significant reduction in canker sore outbreaks and symptoms was observed after several months of consistent B-12 treatment in some studies. However, some topical B-12 applications have shown pain relief within days.

If you experience recurrent canker sores, it is wise to check for other nutritional deficiencies, particularly iron, folate (folic acid), and zinc, as these are also linked to oral ulcers.

Sublingual B-12 supplements (tablets or lozenges dissolved under the tongue) are sometimes suggested for canker sores, as they may bypass potential absorption issues in the gut. Studies have explored the effectiveness of consistent daily supplementation over several months.