What Are Food Allergies

skinnylicious

Have you ever gotten hives after eating? It might be a food allergy. Learn what causes these allergies, and why they can be so serious.

Related Videos:
Food Allergy Substitutes | HealthiNation

Local Honey & Allergies Myth | HealthiNation

Overview

Food allergies affect about 11 million Americans and can be serious. Food allergies not only prevent people from enjoying certain foods, but may also make it difficult to get the nutrients needed for overall health.

How Food Allergies Develop

Food allergies occur when a particular food triggers the body’s immune system to develop an allergic reaction. It only takes a small amount of the food for this to occur. An allergic reaction can develop immediately or over a few hours and can range from hives to more serious complications such anaphylaxis, which can be fatal.

Symptoms of a Food Allergy

Symptoms of food allergies include:
Hives. These are small, itchy red bumps that look like wheels, or blotches, on the skin.
Eczema. This is an itchy, dry patch of skin.
Asthma-like symptoms. Some people may wheeze or cough from a food allergy.
Diarrhea and vomiting.
Itching of the mouth and throat.
Swelling in the mouth and throat.
Abdominal pain.

These symptoms can signal a food allergy, but some of them can also be caused by food intolerance. For example, people who are lactose intolerant may feel sick after drinking milk, but this does not mean that they are allergic to milk. The difference is that the discomfort from food intolerance is not caused by the immune system and is thus not an allergy.

Common Food Allergies

Some of the most common food allergies are to nuts, dairy products, wheat, and certain fish. These reactions start when a natural immune system antibody called immunoglobin E – or IgE – triggers the release of histamine and other chemicals. The chemical histamine causes allergy symptoms like hives and sneezing.

Diagnosis of Food Allergies
People should visit an allergist to find out if they have a food allergy. An allergist will ask questions about family history and the symptoms caused by certain foods. A skin test may be done using liquid extracts of different foods. If a certain extract causes hives or a rash, this can confirm a food allergy. A blood test may also be performed to test for IgE antibodies to specific foods.

An elimination diet may be useful in diagnosing a food allergy. This works by avoiding the suspected food to see if allergy symptoms resolve. If the symptoms do resolve, the next step is to do a food challenge. This involves eating the suspected food and seeing whether there is a reaction. If there is, the allergy is confirmed.

It may also help to keep a food diary, which details what food is eaten, when and any symptoms that appear around that time.

Sources:
Eggs. Fairfax, VA.: The Food Allergy and Anaphylaxis Network, 2009. (Accessed March 17, 2009 at http://www.foodallergy.org/page/eggs.)

Fish. Fairfax, VA.: The Food Allergy and Anaphylaxis Network, 2009. (Accessed March 17, 2009 at http://www.foodallergy.org/page/fish1.)

Guidelines for the Diagnosis and Management of Food Allergy in the United States. Washington D.C.: National Institute of Allergy and Infectious Disease, December 2010. (Accessed May 4, 2011 at http://www.niaid.nih.gov/topics/foodallergy/clinical/Pages/default.aspx.)

Milk. Fairfax, VA.: The Food Allergy and Anaphylaxis Network, 2009. (Accessed March 17, 2009 at http://www.foodallergy.org/page/milk1.)

Peanuts. Fairfax, VA.: The Food Allergy and Anaphylaxis Network, 2009. (Accessed March 17, 2009 at http://www.foodallergy.org/page/peanuts.)

Soy. Fairfax, VA.: The Food Allergy and Anaphylaxis Network, 2009. (Accessed March 17, 2009 at http://www.foodallergy.org/page/soy1.)

Wang J, Sampson H. Food Allergy. The Journal of Clinical Investigation 2011;121:827-835.