Can you develop food allergies, such as grains, as an adult? how are they diagnosed? what treatment is there?

At any age: Food allergies can occur at any age although more likely in children. One must be careful not to assume that all food "reactions" are allergic. Diagnosis is done with a combination of history, skin testing (or blood tests), and possible food challenge. These should be done under the direction of a specialist (usually board certified allergist).