B-6, Niacin, B-12, and Folic Acid all exacerbate my facial burning, even the tiny amounts present in a fortified snack bar or breakfast cereal. To be more accurate, I notice the problem after eating six snack bars in a row or two or three bowls of raisin bran, so obviously the total amount of B vitamins consumed has something to do with it. This sensitivity only became obvious some 4-6 months ago. Didn't notice any problem with it before then. Eating foods that are naturally high in B vitamins, such as liver, seem to produce far less severe symptoms.