Sulfitizing agents such as sulfur dioxide and sodium and potassium salts of bisulfite, sulfite, and metabisulfite are used as preservatives in food, beverages, and pharmaceuticals. It is known that patients with allergic diseases, including bronchial asthma, often experience clinical symptoms after eating foods containing sulfonating substances. In many regions of the world, sulfites are now among the potential allergens that should be labeled on food and beverages.