Canker Sores: The Gut and Immune Connection Behind Mouth Ulcers

Those Painful White Spots Inside Your Mouth

Canker sores (aphthous ulcers) — small, painful, white or grey ulcers with a red border inside the mouth — affect up to 20% of the population and are among the most common oral complaints in Nigeria. For many people, they recur monthly or even more frequently, significantly affecting eating, speaking, and quality of life.

Why You Keep Getting Them

• Nutritional deficiencies — iron, B12, folate, and zinc deficiency are strongly associated with recurrent aphthous stomatitis (RAS). Correcting these deficiencies alone reduces or eliminates recurrence in many patients
• Coeliac disease — a significant percentage of people with frequent mouth ulcers have undiagnosed coeliac disease or non-coeliac gluten sensitivity
• Gut dysbiosis — the oral microbiome and gut microbiome are connected; gut dysbiosis alters immune regulation in the mouth
• Stress — the most commonly reported trigger; cortisol shifts immune balance toward inflammatory pathways
• Sodium lauryl sulphate (SLS) — a foaming agent in most toothpastes shown to increase aphthous ulcer frequency

The FXMed Assessment

Recurrent mouth ulcers warrant: B12, folate, ferritin, zinc, and coeliac antibodies (tTG-IgA) at minimum. Our Gut Repair Programme addresses the gut dysbiosis and nutrient malabsorption underlying many cases of RAS. Something as simple as switching to an SLS-free toothpaste and addressing B12 deficiency can transform recurrence rates.