Food Allergies and Food Intolerances


Definition

A food allergy is a specific reaction to a substance when it is ingested. While the reaction may appear (present) in a variety of forms, what is actually happening is the body is having an immune reaction and is producing antibodies, called IgE (Immunoglobulin E) to "fight" the substance. A few forms the allergic reaction can take are hives, eczema, asthma, or in a worst case, difficulty breathing and even death.

It is possible to test for allergies by a skin prick test or a blood test. A skin prick test is performed in a doctor's office by applying different substances to the skin and pricking the skin to see if the body reacts. The blood test is called RAST (RadioAllergoSorbent Test) and is performed in a lab to test how much the body reacts when exposed to substances.

These tests have varying degrees of accuracy especially in young children. Although it is not common, it is possible for a child to test negative for allergy to a substance and yet have a strong reaction when exposed to it at home.

A food intolerance is different from an allergy because the person does not produce the IgE antibodies. Food intolerance is a term to describe a number of conditions which are not an allergy but the person cannot eat certain foods. Most food intolerances are not immediately life threatening but can still be quite serious.

Some of the more common food intolerances are lactose intolerance in which a person cannot consume milk products, or celiac disease, a genetic disorder in which a person cannot digest gluten (wheat).

Because a food intolerance does not produce IgE it is usually not detectable with a lab test. An exception to this rule is celiac disease which can be detected with a lab test. For other intolerances the way most people determine food intolerances is by eliminating those foods from their diet.

Treatment

Whether the person has an allergy or an intolerance the treatment is the same, avoidance of that food. This can be complex when the food in question is a staple food for someone's diet or when it is frequently used in making other foods. Soy, eggs and milk appear in many foods where you wouldn't expect it and they appear under a variety of names. For example, I have found all of the following words for items that contain egg or egg proteins:

Eggs are used to clarify some root beer and wine, they are used to make breads shiny, they are a major ingredient in meringue and marshmallows, not to mention that the majority of baked goods call for egg. Egg can also appear in medicines, I have heard that Propofol is an anesthetic that has eggs and soy in it, and the MMR immunization (Measles Mumps Rubella) is cultured in chicken eggs. I have heard a variety of opinions on giving MMR to children who have an egg allergy and since Margaret has not received hers I cannot say if a child with an egg allergy should avoid this immunization.

Most common food allergens

Peanuts are in a separate category as they are actually a ground nut. There is also a movement to add sesame to the list of most common food allergens.

The list above has the most common food allergies but it is possible to be allergic or intolerant of any food, not just those on this list.

Further Information







This page is copyright 2005, Laura Giletti
Last revised: December 2005