My partner (female, 57) has suffered with mouth cankers for as long as she can remember. These are/were incredibly painful. They looked like mini volcano's! They came 'round on a regular basis on gums, tongue and inner lips. We tried just about everything, but with no joy. Then I thought maybe she is gluten sensitive (I had heavily researched gluten sensitivity for my own [now cured skin condition[s], see elsewhere on Earthclinic), and other other 'odd' and seemingly incurable autoimmune-like issues of various friends. The result? Bam! No more mouth cankers. What a joy! To those who do not suffer this issue you just cannot believe the sheer relief that this has brought her. 50 years of doctors efforts had come to nothing. It has now been 2/3 months with no sign of mouth ulcers.
As an aside I would suggest to ANYONE that if you have some sort of seemingly incurable issue (candida, cankers, anaemia, IBS, ear pain, brain fog, rheumatoid arthritis etc., etc. , or indeed... Whatever) that you very, very strongly consider some form of gluten sensitivity. Sadly my partners father also suffers from canker issue (and stomach problems), but as he is 85 and bread is something of a holy social and ethnic issue with him he will just not accept the fact that gluten is his problem. Nevertheless we will keep trying to convince him!
For years I suffered from canker sores, joint pain, sudden weakness, sharp pains throughout my body, and acid reflux. When the stomach cramps set in, that was the red flag: I was gluten intolerant. For those of you suffering from chronic canker sores, it is a food allergy and one of the symptoms of gluten intolerance. As damage occurs to your intestines, your ability to absorb certain vitamins (like vitamin B) can cause your immune system to attack the inside of your mouth because it responds to certain substances that may be left behind after eating.
For me, the trigger was citric acid, but the primary cause was gluten. Now I don't get canker sores unless I eat something with gluten in it. I can even have drinks and foods with citric acid in it and not get them if I'm avoiding gluten. If you are only getting them infrequently then I would suspect that you are just low in vitamin B, but for those of you getting this painful mouth ulcer regularly, you might want to get tested for gluten intolerance. Just thought I'd put in my experiences and two-cents since I see so many myths circulating around about canker sores since there is no definite answer on what causes them.
I am age 83. I suffered from canker sores continuously my whole life until 2 years ago when by accident I discovered that I had celiac disease, that is gluten intolerance. Since going on a gluten-free diet I have not had even one canker sore. NADA! Also the acid reflux that I had all my adult life has also almost completely gone away.