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There are several different types of allergy testing – some scientifically robust, some not. Before committing to an allergy test, it’s essential to understand the scientific validation – and, therefore, legitimacy and therapeutic value – that underpins the chosen test.
Many of our patients have already had tests done through their doctor or dermatologist, and others want advice about which tests to do.
What we recommend depends on the symptom picture and other factors such as:
- Does this person have one or more allergic condition?
- What is the family history?
- Do they present with many high histamine symptoms?
- Do they appear to be triggered more by dietary or environmental allergens?
- What tests have already been done and how reliable are those results?
So, what is a food intolerance anyway? It is an Immunoglobulin G (IgG) mediated food allergy, as opposed to an Immunoglobulin E (IgE) mediated food allergy, which generates a more rapid response to a food. You can do blood tests for IgG-mediated allergies. Serum tests in verified labs are most accurate, as they can detect antibodies in the blood to specific foods.
IgE-mediated reactions are considered ‘true allergies’ and are associated with immediate and sometimes severe reactions, including potentially fatal anaphylaxis. Symptoms such as rash, hives, wheezing, coughing, a runny nose, vomiting, swelling of the lips, tongue or throat, tearing or redness of the eyes, or even a weak pulse and loss of consciousness can develop rapidly (i.e. within seconds) or build over a period of hours (i.e. as long as 72 hours post-exposure). Common foods that trigger IgE allergies include peanuts, tree nuts, shellfish, eggs, dairy products, soy and wheat.
Although rarely life threatening, food intolerance (IgG) symptoms can have a debilitating impact on the quality of life, and lead to chronic health problems including skin and autoimmune disease, and digestive and mood disorders. The incidence of food intolerance is extremely high, estimated as high as 45% of a given population.
After assessing a patient, we might advise them to request a skin-prick test through their GP for IgE-mediated food and/or environmental allergies. This is particularly reliable for detecting environmental allergies to things like dust mites, grasses, pollens, animals, mould and certain trees.
A RAST (Radioallergosorbent) test, which detects antibodies in the blood, might be advised to confirm an IgE food allergy, especially if the patient is too young or the skin too damaged to perform a skin-prick test.
We may offer IgG-mediated food intolerance testing if the patient has no confirmed IgE allergies and their symptoms are not resolving following our Dietary Guidelines.
Unfortunately, IgG allergy tests are not funded through Health NZ – Te Whatu Ora, but any Registered Naturopath can order a serum IgG test for you*.
*Note that these tests are only available to existing patients at our clinic, as they require follow-up advice and protocols.
