Below is an instruction from Human. Write a response.
    ### Instruction:
    What is (are) Food Allergy ?
    ### Response:
    Food allergy is an abnormal response to a food triggered by your body's immune system.    In adults, the foods that most often trigger allergic reactions include fish, shellfish, peanuts, and tree nuts, such as walnuts. Problem foods for children can include eggs, milk, peanuts, tree nuts, soy, and wheat.
    