Allergen

Substance that causes an allergic reaction.

Allergens are found almost everywhere in the environment. They occur in animal hair, pollen, insect bites, house dust mites, pharmaceuticals, and food. Currently, some 20,000 allergens have been identified.

Most allergens in food are proteins of high molecular weight and are rather resistant to gastric acid and digestive enzymes.

An allergenic food may contain several allergens; e.g. there are 15 or more different allergens in soybeans.