An allergic reaction to food is a two-step process.
Step 1:
The frst time you are exposed to a food allergen, your
immune system reacts as if the food were harmful and makes
specifc IgE antibodies to that allergen. The antibodies circulate
through your blood and attach to mast cells and basophils.
Mast cells are found in all body tissues, especially in areas of
your body that are typical sites of allergic reactions. Those sites
include your nose, throat, lungs, skin, and gastrointestinal (GI)
tract. Basophils are found in your blood and also in tissues that
have become infamed due to an allergic reaction.
Step 2:
The next time you are exposed to the same food allergen,
it binds to the IgE antibodies that are attached to the mast cells
and basophils. The binding signals the cells to release massive
amounts of chemicals such as histamine. Depending on the
tissue in which they are released, these chemicals will cause you
to have various symptoms of food allergy. The symptoms can
range from mild to severe. A severe allergic reaction can include
a potentially life-threatening reaction called anaphylaxis.
Generally, you are at greater risk for developing a food allergy
if you come from a family in which allergies are common.
These allergies are not necessarily food allergies but perhaps
other allergic diseases, such as asthma, eczema (atopic
dermatitis), or allergic rhinitis (hay fever). If you have two
parents who have allergies, you are more likely to develop
food allergy than someone with one parent who has allergies.
An allergic reaction to food usually takes place within a few
minutes to several hours after exposure to the allergen. The
process of eating and digesting food and the location of mast
cells both affect the timing and location of the reaction.
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