<<Disclaimer: Verify this information before applying it to your situation.>> I went on a gluten free diet when I finally realized that wheat, rye and barley were causing me to get canker sores without end. I have found recently that if I overdose on olives (I think it is either green or ripe, that is, black olives) I will get one or more canker sores on the lips or under the tongue. I don't know much about these olives except they are large, and come loose in olive oil, are sometimes stuffed, but generally not - that is, they have stones - and when I crave olives I like to eat maybe a dozen at a time! The sores seem to begin as tiny clear blisters. I can sometimes keep them from developing into big canker sores by repeated application of a povidone-iodine solution. Has anyone else found this problem with olives? I wonder if it is something in the olives themselves that behaves in the same way as gluten or is there gluten somehow in the olives.