The Science Based Medicine website has in depth and detailed reviews on a wide range of subjects.
From their website;
Food allergies can be as real as drug allergies, and are arguably much harder to prevent. We can usually control when we get penicillin. But what about peanuts, eggs, or milk, all of which can also cause life-threatening anaphylaxis? Food allergies seems to be growing: not only anaphylaxis, butmore people believe they have some sort of allergy to food. Allergy is sometimes confused with the term “intolerance”, which seems more common, possibly as the availability of “food intolerance testing” grows. Food intolerance testing and screening is particularly popular among alternative practitioners. Testing can take different forms, but generally the consumer is screened against hundreds of food products and food additives. They are then provided with a list of foods they are “intolerant” to. … Children may be tested, too, and parents may be given a long list of foods they are told their child is intolerant of. I’ve seen the effects in the community, too. Think going “peanut free” is tough? A public school in my area sent home a list of forbidden food products: dairy, eggs, bananas, tree nuts, peanuts, soy, sesame, flax seed, kiwi, chicken, and bacon. Were these all true allergies? It’s not disclosed. Anaphylactic or not, the parents had informed the school, and the school had banned the food product.
At present, there are no reliable and validated clinical tests for the diagnosis of food intolerance. While intolerances are non-immune by definition, IgG testing is actively promoted for diagnosis, and to guide management. These tests lack both a sound scientific rationale and evidence of effectiveness. The lack of correlation between results and actual symptoms, and the risks resulting from unnecessary food avoidance, escalate the potential for harm from this test. Further, there is no published clinical evidence to support the use of IgG tests to determine the need for vitamins or supplements. In light of the lack of clinical relevance, and the potential for harm resulting from their use, allergy and immunology organizations worldwide advise against the use of IgG testing for food intolerance.
there’s a big gap between what many perceive as an allergy and what is clinically considered a true allergy