Which do you measure: IgE, IgG, IgG4, C3d? Well, it depends what you are looking for as some will measure classical allergies, others for tolerance building to those allergies, some for delayed intolerances and other for major inflammatory reactive foods. I go for all of ’em in one fingerprick test, which makes life a lot easier!
I thought this was a useful reminder today from Precision Point Diagnostics – they do the P88 Allergy test that I really rate. You can see my video on the P88 here for more if it interests you.
IgE measures the intensity of an [classical] allergic reaction to that particular food.
IgG4 measures the degree of mediation (tolerance) to an IgE reaction from a particular food. The P88 report shows both IgE and IgG4 reactions side by side for ease of interpretation.
IgG measures food sensitivities, not true [classical] food allergies. Food sensitivities tend to have a longer time of onset for symptoms to appear, from 3-72 hours usually. Food sensitivity symptoms can vary from those caused by food allergies and can include headaches, fatigue, brain fog, general inflammation, and digestive upset [amongst loads of others!].
Complement (C3d) measures the capacity for a complement cascade to be triggered by an IgG reaction from a particular food. Such a cascade can cause a surge in inflammatory action that can be 1,000 times greater than that which may occur without the cascade.
They continue with a bit more technical explanation:
The Precision Point Diagnostics P88 Dietary Antigen Test measures four different immunological reactions to 88 different foods, IgE (food allergies), IgG (food sensitivities), IgG4 (food tolerance), and C3d (complement- which in our case is a measure of the risk for a “complement cascade” associated with the IgG reaction, which means that a much more severe reaction is identified with that food that could be 1,000 to 10,000 the normal immunological response.
Most food allergy and sensitivity testing (dietary antigen testing) are not nearly as multifaceted, rigorous, or as complex as that offered by Precision Point Diagnostics. There are some dietary antigen tests available, both here and in other countries (In Europe especially) that test only IgG4 as a method for detecting food sensitivities. This used to be more common but really hasn’t been the standard for 20 years or more.
We’ve learned a lot more about the immunology of food allergies and food sensitivities in the intervening years.
IgG4 measurements show a mediation of IgG reactions. In other words, when IgG4 measurements are positive, then it demonstrates a tolerance to allergic reactions to that same food. So, depending on how severe the IgE reaction, and how strong the IgG4 measurement, it may be that a patient has developed a safe tolerance to a food that they were once allergic to, or put another way, a patient’s allergic reaction has been overcome by IgG4 developed tolerance to that food and that food can be safely consumed.
On the other hand, if the IgE reaction is stronger than the IgG4 reaction, but still not an extreme allergy, then it likely demonstrates that a tolerance to that food is building and a cautious diet that builds on that tolerance to increase it may be warranted. Highly allergenic foods will likely continue to be avoided without a special protocol for desensitization administered by the practitioner.
The point is, it’s complicated, and based on fairly complex immunological science.
Sometimes conventional medicine is slow to catch up. For instance, the European Union recommends against using IgG4 as a testing method to determine food intolerance: Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI Task Force Report states “Serological tests for immunoglobulin G4 (IgG4) against foods are persistently promoted for the diagnosis of food-induced hypersensitivity.” and “In contrast to the disputed beliefs, IgG4 against foods indicates that the organism has been repeatedly exposed to food components, recognized as foreign proteins by the immune system. Its presence should not be considered as a factor which induces hypersensitivity, but rather as an indicator for immunological tolerance, linked to the activity of regulatory T cells.” Clearly, the EU is concerned with labs that use IgG4 as a marker of sensitivity, and point out that it instead indicates tolerance- which is exactly how the P88 assesses IgG4.
So, hope that is a tad clearer. If in doubt, watch my video where I explain it all in lay terms and take you through the report. They have just updated the report a bit so it might look a tiny bit different – I’ll have to do a new one for you when I get a chance! I’m just focusing on the new Hormone Plan at the moment, which is enough in m y head for a bit!