Food Allergy: What You Need to Know

Stephanie A. Leonard, MD


November 15, 2010

In This Article

What Is Food Allergy?

Food allergy is an immunoglobulin (Ig)E- or non-IgE-mediated immune response to food protein. This column will focus on IgE-mediated food allergy represented by immediate hypersensitivity (Gell-Coombs Type I), which can include anaphylaxis and can be life-threatening. Non-IgE-mediated reactions are thought to be cell mediated (allergic eosinophilic esophagitis/gastroenteritis, food protein-induced proctocolitis, food protein-induced enterocolitis syndrome, food protein-induced enteropathy [including celiac disease], and food-induced pulmonary hemosiderosis).

Adverse reactions to foods are sometimes confused with food allergies, but these reactions are nonimmunologic. Nonimmunologic food reactions can be metabolic (lactose intolerance), pharmacologic (chemical migraine triggers such as tyramine, aspartame, monosodium glutamate, nitrates/nitrites, alcohol, coffee, and chocolate), or toxic (scombroid poisoning or food poisoning) in origin. Lactose intolerance can be managed with replacement of the enzyme lactase. Symptoms of scombroid poisoning, associated with bacterial histamine build-up in contaminated fish such as tuna or mackerel, can appear similar to an allergic reaction; affected patients respond well to antihistamines.[1] In contrast to food allergy, food poisoning often occurs in clusters and is not reproducible.


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