Food Allergens: History, Physical Examination, and Molecular Structure

Food allergy is an IgE-mediated immune response to specific food substances which triggers mild to severe anaphylactic reactions in a highly sensitized allergic individual. The World Allergy Organization and the European Academy of Allergy and Clinical Immunology classified various types of allergic diseases. The US Food and Drug Administration (FDA) currently prioritizes big eight foods, namely, milk, egg, fish, wheat, tree nuts, legumes (specifically peanuts and soybeans), crustaceans, and mollusks, which are strongly associated with severe allergic reactions in highly sensitized individuals. Sesame has emerged as the ninth most common food allergen in the USA following the enactment of the Food Allergy Safety, Treatment, Education, and Research (FASTER) Act on April 23, 2021. Physical examinations diagnose immediate acute reactions and recurring symptoms which differentiate food allergy, asthma, allergic rhinitis, and atopic dermatitis. The molecular structures of food allergens are typically proteins or glycoproteins in nature. These allergenic proteins ably elicit IgE-mediated allergic immune response via mast cell degranulation and release secondary mediators, which causes allergic symptoms. This chapter is dedicated to exploring the historical context, physical examination and diagnosis methodology, and molecular compositions of allergenic proteins derived from various foods and their properties.