Allergies vs Chemical Reactions in the Body

Intolerance to certain foods, especially gluten (wheat related grains) and casein (milk protein), is a common occurrence among children with developmental delays. Before adopting an elimination diet, however, many parents consult an allergist to determine if the diet is necessary. Surprisingly, after extensive scratch testing, the child is often found not to be allergic to any foods. Some parents choose to eliminate gluten and casein proteins anyway, and find their youngster responds with improved attention, sleep and/or language skills.

How is this improvement possible if the child was not allergic in the first place? The answer lies in understanding the difference between allergies and other types of chemical reactions within the body.

IgE versus IgG Reactions

Allergies are defined as specific reactions within the immune system involving an antibody called immunoglobulin E (IgE). Immediate responses such as hives, congestion or swelling typically result from IgE activity. Traditional scratch testing identifies IgE triggers such as pollen or peanuts, which can cause symptoms that range from annoying to lethal.

Very different responses are delayed allergy reactions. If they occur more than two hours after eating a food, they may result from immunoglobulin G (IgG) rather than IgE activity. IgG reactions may cause symptoms such as sleep disturbances, subsequent bed wetting, sinus and ear infections, or crankiness. Blood tests rather than scratch tests are the only way to screen for IgG allergies.

Where immunoglobulins are involved, the word “allergy” can legitimately be used to describe symptoms after exposure. A reaction to gluten or casein sometimes shows up in IgG or IgA blood testing, and is, therefore, referred to as an “allergy


Symptoms, Diagnosis Tests and Treatment

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