What Causes Canker Sores?
The exact cause of most canker sores is unknown.
Stress or tissue injury is thought to be the cause of simple canker sores. Certain foods - including citrus or acidic
fruits and vegetables (such as lemons, oranges, pineapples, apples, figs, tomatoes, and strawberries) - can trigger a canker sore or make the problem worse. Sometimes a sharp
tooth surface or dental appliance, such as
braces or ill-fitting
dentures, might also trigger canker sores.
Some cases of complex canker sores are caused by an underlying health condition, such as an impaired immune system; nutritional problems, such as vitamin B-12, zinc,
folic acid, or iron deficiency; and gastrointestinal tract disease, such as
Celiac disease and
Crohn's disease.