(image thanks to blogs.sciencemag.org)
The immune system guards against foreign invaders. In the case of an allergy, the invaders are called allergens. The primary weapon that it uses against invaders is the production of antibodies. The antibodies cause reactions that result in the offending allergens being removed from the body. In many people, foods act as allergens rather than nutrition. This can result in the symptoms of IBS.
The immune system produces numerous kinds of antibodies, called immunoglobulins. IgE and IgG are acronyms for the two different kinds of antibodies produced by the immune system in allergic reactions to food. You might be asking why you need to know this.
Conventional allergy testing looks for IgE reactions only. These types of reactions typically occur immediately after contact with or ingestion of the allergen, and in some cases can cause serious, even fatal, health problems. Potential IgE reactions include swelling of the lips and tongue, hives, bloating, abdominal pain, or sudden diarrhea. These are the reactions that people usually think of when they hear the word allergy.
However, IgE reactions can also lead to many other symptoms not traditionally recognized as being caused by food allergies.
The problem with this type of testing is that most food allergies are not IgE reactions, but are rather IgG reactions, which usually show up hours or even days after ingestion of the allergen. They are generally not nearly as dramatic as the more severe IgE reactions, and usually result in “mere” constipation, diarrhea, bloating, gas and abdominal pain. Both antibodies are important, and food allergy testing should include both or the cause of IBS may be missed.
For more information about this subject refer to The Irritable Bowel Syndrome Solution.
Great image thanks to sciencemag.org