For adults, extensive food restrictions could lead to a limited an inadequate diet. The antibodies release chemicals, like histamine, that cause symptoms such as itchy skin or runny nose. True food allergies can be life threatening, especially if an anaphylactic reaction occurs. This is a violent, life threatening situation in which the breathing tube swells shut. This can occur within a few seconds or minutes after eating the instigating food.
Food intolerance is more common than food allergy.
The body has trouble digesting a portion of the food, usually because of a chemical deficiency. For example, lactose intolerance occurs when people have trouble digesting milk. They are deficient in the intestinal enzyme lactase, which is needed to digest the milk sugar lactose. In many cases, allergic individuals can blame their family tree. Many infants and children with food allergies outgrow their sensitivities.