Classification of Food Allergens and Cross-Reactivity

Patients with specific food allergies are commonly sensitized to related foods, for example, shrimp with other shellfish and peanut with other legumes. In some instances, this represents a true allergy to the related food, defined as cross-reactivity, while in other instances, it represents a positive skin or IgE test only, in a patient who can eat the related food without difficulty. This is defined as cross-sensitization. It is extremely important that the clinician recognize these patterns of cross-sensitization and cross-reactivity, both to counsel patients on foods that should be avoided and to make sure that foods are not unnecessarily restricted from the diet. In fact, it is very common for patients to be instructed to avoid entire food groups based just on positive tests, which leads to unnecessary dietary restrictions with effects on food choices, nutrition, and quality of life.