Food Allergen

What Is a Food Allergen?

A food allergen is a protein in food that triggers an abnormal immune response in sensitized individuals. During an allergic reaction, the immune system mistakenly identifies a harmless food protein as a threat, producing immunoglobulin E (IgE) antibodies. On subsequent exposures, these antibodies trigger the release of histamine and other mediators from mast cells and basophils, causing symptoms that range from mild (hives, itching) to life-threatening (anaphylaxis).

Food allergies affect an estimated 6–8% of children and 2–3% of adults. They are distinct from food intolerances (such as lactose intolerance), which involve digestive difficulty rather than immune-mediated reactions.

The Major Food Allergens

In the United States, the Food Allergen Labeling and Consumer Protection Act (FALCPA) and the FASTER Act (2021) require clear labeling of nine major allergens, which account for approximately 90% of serious food allergy reactions:

• Milk
• Eggs
• Fish (e.g., bass, flounder, cod)
• Shellfish (e.g., crab, lobster, shrimp)
• Tree nuts (e.g., almonds, walnuts, pecans)
• Peanuts
• Wheat
• Soybeans
• Sesame (added as the ninth major allergen effective January 2023)

Managing Food Allergies

The only effective management for food allergies is strict avoidance of the allergen. Individuals with severe allergies should carry injectable epinephrine (an auto-injector such as an EpiPen) at all times. Cross-contact — when an allergen is unintentionally transferred from one food to another — poses a significant risk in restaurant and shared kitchen settings. Oral immunotherapy (OIT) for peanut allergy has received FDA approval and can reduce reaction severity, though it does not cure the allergy. Food allergies in children may resolve with age; peanut, tree nut, fish, and shellfish allergies tend to be lifelong.