What is a Food Allergy?
Food allergy is the term used to refer to reactions (or a health effect) caused by a specific immune response from exposure to a food protein and is therefore immune system mediated. The immune system can react using antibodies or directly with white blood cells, skipping the intermediate antibody step. When the immune system is NOT the cause of a reaction to a food, it is referred to as a food intolerance.
There are multiple types of food allergy, each with distinct pathophysiologic features, yet broadly categorized into the following immunological processes:
There are multiple types of food allergy, each with distinct pathophysiologic features, yet broadly categorized into the following immunological processes:
- IgE-mediated food allergy (FA), or "classic food allergy," is the most common characterized by acute reactions with rapid onset. The body’s immune system mistakes the food protein as harmful, therefore triggering the production of immunoglobulin E (IgE) antibodies to neutralize the protein (allergen). Then each time the body is exposed to this specific food protein, these IgE antibodies recognize them and signal the immune system to release histamine and other chemicals. Histamine and other body chemicals then cause a range of allergic reactions from mild to severe symptoms, the most severe being potentially fatal anaphylaxis.
- Non-IgE-mediated food allergy (NFA), also referred to as "Cell-mediated," occurs when other immune processes are responsible for a reaction to a food protein and characterized by delayed and non-acute reactions. Most of these reactions involve the gastrointestinal tract and rarely life threatening; since no IgE antibodies are present then there is no potential for anaphylaxis. It is to be noted however that Non-IgE mediated food allergy may convert to IgE mediated food allergy. Food Protein Induced Enterocolitis Syndrome (FPIES) and Milk-Soy Protein Intolerance (MSPI) are both examples yet Celiac Disease is both autoimmune and non-IgE-mediated.
- Mixed IgE- and non-IgE-mediated results when abnormal immunological and metabolic processes are occurring within the body. An example of a mixed disorder, Eosinophilic esophagitis (EoE) is an allergic inflammatory disease that may or may not be anaphylactic.
Food Allergy vs Food Intolerance
A FOOD ALLERGY occurs when the immune system reacts to a food protein as if it is a harmful invader, causing symptoms within seconds to hours after eating or simply coming into contact with the food. These symptoms can affect the respiratory system, gastrointestinal tract, skin, and/or cardiovascular system. Reactions may be fatal within minutes so IMMEDIATE emergency treatment is needed - Inject Epinephrine and call 911.
Except for Milk-Soy Protein Intolerance (MSPI), a FOOD INTOLERANCE is caused by toxins (poison), metabolic, pharmacologic or idiosyncratic processes within the body that do NOT involve the immune system. They are generally less serious (non life threatening) and usually limited to digestive problems however other symptoms do occur often. A food intolerance is unlikely to cause an anaphylactic reaction.
Information approved by FACET's Medical Advisor
Image from http://www.allergygoaway.com
Website information should not substitute for seeking responsible, professional medical care.
First created 2012, last updated 2014
Except for Milk-Soy Protein Intolerance (MSPI), a FOOD INTOLERANCE is caused by toxins (poison), metabolic, pharmacologic or idiosyncratic processes within the body that do NOT involve the immune system. They are generally less serious (non life threatening) and usually limited to digestive problems however other symptoms do occur often. A food intolerance is unlikely to cause an anaphylactic reaction.
Information approved by FACET's Medical Advisor
Image from http://www.allergygoaway.com
Website information should not substitute for seeking responsible, professional medical care.
First created 2012, last updated 2014
