- Compounds, either proteins or smaller chemicals, which react with the proteins of the skin and mucous membranes (eyes, nose, lungs, gut, etc.) of some persons to elicit the immune response of the body causing rashes, irritation, asthma, etc. Typical food allergies occur with strawberries, eggs, milk, cereal, fish, peas, and nuts. The response should not be confused with that produced by enzyme deficiencies as e.g. with the inability to metabolize lactose, found in most Chinese, and the inability to metabolize gluten, which is fairly common in the West.