Food Sensitivities and Special Diets

A food allergy is an abnormal immune response, most commonly mediated by immunoglobulin E (IgE) antibodies, in which the immune system mistakenly identifies a specific food protein as a threat, triggering a cascade of symptoms that can range from mild hives to life-threatening anaphylaxis. In the United States, nine allergens are formally recognized as responsible for the large majority of significant reactions: milk, eggs, peanuts, tree nuts, wheat, soy, fish, shellfish, and, as of a 2023 labeling law, sesame. Food allergy prevalence has risen in many high-income countries in recent decades, prompting research into explanations such as the "hygiene hypothesis" and the "dual-allergen-exposure hypothesis," which proposes that early skin exposure to food proteins (for instance through eczema-affected skin) without corresponding oral exposure can promote allergic sensitization. This latter hypothesis helped motivate the Learning Early about Peanut Allergy (LEAP) trial, whose findings prompted a significant revision of pediatric guidance toward earlier, rather than delayed, introduction of peanut-containing foods in infancy.