Food allergens refer to specific proteins or other components in food that can cause an adverse immune response when consumed by individuals with a pre-existing allergy. These substances are typically harmless for most people, but they can trigger symptoms such as itching, swelling, and difficulty breathing in those who have developed an allergy to them. Common food allergens include peanuts, tree nuts, dairy products, eggs, fish, shellfish, soybeans, wheat, and certain fruits like strawberries or kiwi.