A food allergy is any adverse reaction to a food or food component involving the body's
. Some adverse
reactions to foods do not involve the immune system and are known as , e.g. food poisoning or the
inability to properly digest certain food components such as or
A true allergic reaction to a food involves two primary components:
Contact with food (part of the food that stimulates the immune system);
Immunoglobulin E ( : an in the immune system that reacts with )
and (tissue cells) as well as (blood cells), which release
or other substances
causing allergic symptoms when IgE antibodies attach onto these cells.
Although most Americans consume a wide variety of food additives daily, only a small number have been
associated with reactions. These reactions do not involve the immune system and therefore are examples
of food intolerance rather than food allergy.
While most allergic reactions to food are relatively mild, a small percentage of food-allergic individuals
have severe reactions that can be life-threatening. is a rare but
potentially fatal condition in
which several different parts of the body experience food-allergic reactions simultaneously, causing
swelling of the throat and difficulty in breathing.
Food allergies can cause a host of , including : swelling of the lips;
tongue or throat; hoarseness;
cough; ; skin ; a runny nose and watering eyes; and
. Sometimes symptoms are limited to nausea,
vomiting, or cramping diarrhea. of a food allergy are highly individualistic and usually begin
within minutes to a few hours after having
eaten the offending food.
The most common food allergens involved in food allergy are shellfish, , fish, soy,
, egg and tree nuts such as walnuts.
Pharmacologically active substances found in food include , tyramine,
tryptamine and , which may be consumed in foods such as red wine, cheese,
yeast extract, avocados and bananas. In susceptible people, these foods can trigger
, facial flushing and headaches.
Patients with hypersensitivity to avocados, bananas, kiwis or chestnuts sometimes exhibit clinical reactions to
. This is termed .
There are a variety of forms in which a food hypersensitivity expresses itself. These include:
Gastointestinal disease with an immunologic basis, e.g. ;