IgG food allergy testing

I got this from Bellevue allergy and asthma and I think it explains very well why allergists do not consider the test to be effective.


What is food sensitivity or food intolerance?
Food sensitivity (also called “food intolerance”) has been described as an adverse reaction to a food, but without the classic signs of food allergy: hives, swelling, difficulty breathing, etc. With food sensitivity, patients report a wide variety of symptoms including abdominal discomfort, malaise, headache, fatigue, and behavior problems. These symptoms are real, but it is difficult to know if they are related to food, or maybe something completely different (e.g. a different medical problem, stress, or a lack of sleep or exercise).

What is IgG or IgG4 testing?
IgG or IgG4 testing (sometimes called a “food allergy panel”) is a screening blood test that has gained popularity in the past several years. Its supporters believe the test can determine the foods to which you are allergic or sensitive. When you stop eating those foods, your symptoms, whichever they may be, will go away. In reality, it is probably not so simple.
IgG, or “immune globulin G”, is a naturally occurring antibody generated by the immune system. We know that IgG antibodies play an important role in fighting off infections. For unknown reasons, the immune system also makes IgG antibodies to many of the foods we eat. IgG directed at a food isn’t necessarily harmful: healthy individuals can have elevated IgG levels to a particular food(s), yet have no symptoms at all. In fact, food allergy researchers are finding that higher IgG levels may actually protect against food allergy2-3. It goes to show that there is still much to learn about food allergy/sensitivity and the immune system.


This is the explanation I like....

Why does the Allergist community speak against IgG food allergy testing?

One of our goals is to help patients make informed choices about their health care. Therefore, it must be said that IgG testing has not been scientifically proven to predict food allergies, food sensitivity, or food intolerance. While the test can accurately measure IgG levels to numerous foods, we do not know what those levels actually mean. For example, if a patient has an elevated IgG level to milk, does it mean the person is sensitive to milk, or does it simply confirm there is milk in the person’s diet? The IgG test cannot tell us the difference.






http://www.allassoc.com/problems-with-igg-food-allergy-testing/