Hidden Casein is trace amounts of casein which may or may not exist in processed food or food eaten in restaurants or cafes.

People on casein-free or gluten-free casein-free diets tend to regard all mysterious reactions to foods as being caused by trace amounts of casein or gluten.

In reality individuals who have intolerances to gluten and casein react with a dose-related response and are rarely sensitive enough to react to trace amounts of casein, but are reacting to other artificial additives or natural food chemicals.

The exception to this rule is when a genuine IgE allergy exists to casein or gluten, as allergic responses are not dose-related.