 Recurrent canker source is the single most common inflammatory and ulcerative condition of the mouth, affecting as many as one in five people. Ouch! Sometimes it can be a sign of celiac disease, a relatively rare autoimmune condition triggered by the wheat protein gluten. But what about those without celiac disease? Well, 37 years ago there was a report of a small group of recurrent canker source patients that got better after removing gluten from their diet, despite the fact that they didn't have any signs of celiac disease. Now without a control group, you don't know if they wouldn't just gotten better on their own, but it was interesting enough to spark further study. Given that small series of patients, they decided to try out a gluten-free diet on 20 folks with recurring canker source, again explicitly excluding those known to have celiac disease. And five out of 20 seem to get better. And critically, then they got worse when they were challenged with gluten. So even though there was no control group in the few that got better, the ulcers came back when gluten was added back to their diet. Now this was not just some random group of canker source sufferers. The reason they had gotten intestinal biopsies to rule out celiac was because they had some other abnormalities. So you can't extrapolate from this study saying one in five sufferers may benefit from cutting out gluten, though at least it appears in some people to help. Though it would have been better if there was some blinded challenge. I mean, if you cut out gluten or any food and just coincidentally happen to feel better, you might convince yourself that gluten was the culprit. So then when the researcher gives you a piece of bread, maybe just the stress that the thought of your ulcers coming back may actually help trigger the ulcers coming back. And that's why ideally you do blinded gluten challenges to see if gluten really is to blame. For example, if you take people who don't have celiac or wheat allergy, but nevertheless claim to be sensitive to gluten, you can test to see if they're fooling themselves by randomly assigning them to take a capsule with gluten inside or just a placebo made out of rice starch. So they're on a gluten-free diet, and then you give them this pill, which in the case of the gluten one is equivalent to like two pieces of bread, and you see if they get worse. And then just the thought of taking something that might be gluten, their symptoms shot up. And this was them just taking a placebo rice starch pill. But the reason we know this non-celiac gluten sensitivity exists is that the actual gluten pill made them feel even worse. And that's specifically what happened in the case of canker source. Those who felt they were gluten sensitive did actually get more canker source exposed to real as opposed to fake gluten. Where did they even get the idea in the original study to try cutting out gluten? Well, back in the 60s it was reported that the blood of patients with bad canker source reacted to certain food proteins, like gluten, but had an even stronger reaction to the milk protein casein. This has since been more formally tested, 50 patients, with recurring canker source were compared to 50 healthy people for their levels of anti-gluten antibodies. Gleadin is a type of gluten protein, an anti-cows milk protein antibodies, and the canker source sufferers were no more likely to react to the gluten, but the levels of anti-milk proteins were significantly higher. In fact, the majority reacted to the cow's milk. These results indicate a strong association between high levels of anti-milk proteins in the blood with recurring canker source. But what we care about is do people actually get better or not when they cut out the milk? Well, upon hearing their results, three of the patients spontaneously decided to cut out all dairy products from their diet for a few months to see what happens, and it seemed to help. No reappearance of the source in the first patient. Same with the second, until they had some cow's milk ice cream. And in the third, the ulcers seemed to come with less frequency, but those were just some observations, not an actual study. You see, the same thing with certain food additives. Folks with recurring canker source may react more to certain food dyes, and so if you try people on a gluten-free diet or a dairy-free diet or a diet free of certain food additives, you'll get a few cases of people responding, in this case, 6 out of 11. Some better on the gluten-free, others better on the milk-free, others on the additive-free. But the responses were pretty dramatic, seen within a week, so it seems it might be worth giving these exclusion diets a try to see if there's a huge improvement. Can you just get an allergy test or something? Apparently not. For example, this poor woman, who suffered from recurring canker source since she was 2 years old, multiple painful lesions in her mouth almost constantly. They asked her about milk, and she said she rarely drank it because it appeared to trigger her more almost immediately, so they decided to look into it. They tested her for sensitivities to dairy, both so-called prick-and-pash allergy tests, and they were both negative. But hey, if she felt worse on dairy, might as well try cutting out all dairy products completely, and for the first time in her life, the ulcers went away and stayed away, unless she actually had some milk product. So even if people test negative, maybe worth a try to cut out all dairy and see what happens. Look, we know cow's milk may play a role in other allergic and autoimmune-type diseases, and there are these reports going back decades suggesting at least there's a subgroup of canker sore patients, for which dairy is a causative factor. However, awareness of this association is rare among both patients and health care providers. An improvement can happen rapidly. A boy and a girl both suffering for years with frequent multiple ulcerations they're apparently cured within two weeks. We don't know how often it works, we just know it does, sometimes. So as this 2017 paper in the Journal of the American Dental Association suggests, why not give a cow's milk protein elimination trial a try, particularly before the use of medications with potential side effects?