The symptoms are often severe, and may even be life-threatening. Food allergies are usually due to the protein component of the offending food. For some reason some of the food protein is absorbed from the intestine intact, instead of being digested as most proteins are. Once the intact protein is in the blood stream, it is recognised as a foreign protein to the body, or in other words as an antigen . This antigen-antibody complex travels around the body and stimulates certain cells, called mast cells, to burst open and to release substances which mediate an allergic reaction.
Histamine is an example of such a mediator.
Histamine causes an inflammatory response in the cells that it reaches, and this inflammatory response is what causes the symptoms of the food allergy. The foods which are the most commonly associated with allergy include milk, eggs, nuts, fish, wheat and chocolate. Reactions can sometimes be avoided or reduced by the use of anti-histamines, or by desensitising therapy, but essentially, people who are allergic to a food should avoid all contact with that food. Food intolerance Food intolerance is the term used to describe a pharmacological reaction to a food component. A pharmacological reaction refers to the drug-like side effects caused by a range of chemicals which may be present in food as natural or added components.