People prone to mouth sores should limit their consumption of foods that contain medium levels of acid, or take precaution measures to limit tissue damage, like following with a food or beverage that is contains low levels of acid. Medium acid fruits and vegetables include apples, apricots, mangos, nectarines, oranges, peaches, pears, plums, tomatoes, green olives and peppers. Cream, cottage cheese and yogurts have medium levels of acid, contrary to most other dairy products. Honey, pesto, mustard, mayonnaise and ketchup are also medium acid dietary items. Wine and buttermilk are medium-acid beverages.