Food Intolerance Testing: Worth the $?
This one you have been asking for for some time now and I am honestly sorry I haven’t covered it earlier as it seems many of you have been through the process of having an IgG Food Intolerance tests done and as you will soon understand it is likely this was not worth the money.
Let’s first get to the basics. What is a food intolerance and what is a food allergy.
ALLERGY VS INTOLERANCE:
A food allergy is an abnormal immune-mediated response to an otherwise harmless food. Food allergies can be categorised into three main types. IgE mediated, Non-IgE mediated and mixed. IgE mediated food allergies typically cause immediate and often life threatening symptoms like anaphylaxis. Typical foods here are peanuts and shellfish. Non-IgE mediated allergies are less well understood but have a more delayed response (usually occurring within a few hours of consumption) and typically cause symptoms like vomiting and diarrhoea. Typical non-IgE mediated allergies are cows milk protein or soy protein.
A food intolerance by definition is a response to a food that DOES NOT involve the immune system. Common food intolerances include MSG, salicylates, amines, lactose and wheat.
When it comes to testing for food allergies and intolerances there are a few options available - not all of which are evidence based or give you the answer you actually want or need.
IgE Testing- Immunologists will often conduct IgE blood testing to determine IgE mediated allergies. Many people already know if they have such allergies as mentioned previously they cause immediate symptoms and can be life threatening. These are the ones we need to be seriously concerned for. They can cause itching skin, throat swelling, vomiting and even anaphylaxis. If you suspect you have a food allergy, get yourself to a GP ASAP.
IgG Testing - These are the tests that you will find widely available through nutritionists, naturopaths or just available to purchase over the internet. IgG is a antibody that signifies exposure to a certain food (not an allergy or intolerance). It is an immune marker showing us that your body recognises and has been exposed to this food. This is not a marker of a negative immune reaction, in fact it can often be a sign of a good level of tolerance to that food. In children who have a cows milk allergy, an increased IgG test shows that they are starting to outgrow the allergy (aka they are better able to tolerate the food). Also let’s keep in mind a food intolerance by definition does not actually involve the immune system.
Ever had one of these tests done and notice foods you consume tend to come up high on the list? Thats because it is showing a normal exposure. So some even suggest that an IgG response to a food is in fact a sign you CAN tolerate this food.
I am sorry if you have been fooled into spending (godly amounts of) money on one of these tests but what you have been told about them is incorrect. They do not show food intolerance.
Read the following statements from
“IgG antibodies to food are commonly detectable in healthy adult patients and children, whether food-related symptoms are present or not. There is no credible evidence that measuring IgG antibodies is useful for diagnosing food allergy or intolerance, nor that IgG antibodies cause symptoms.”
“It is important to understand that this test has never been scientifically proven to be able to accomplish what it reports to do. The scientific studies that are provided to support the use of this test are often out of date, in non-reputable journals and many have not even used the IgG test in question. The presence of IgG is likely a normal response of the immune system to exposure to food. In fact, higher levels of IgG4 to foods may simply be associated with tolerance to those foods”
“The CSACI strongly discourages the practice of food-specific IgG testing for the purposes of identifying or predicting adverse reactions to food. There is no body of research that supports the use of this test to diagnose adverse reactions to food or to predict future adverse reactions. The literature currently suggests that the presence of specific IgG to food is a marker of exposure and tolerance to food, as seen in those participating in oral immunotherapy studies. Hence, positive test results for food-specific IgG are to be expected in normal, healthy adults and children. Furthermore, the inappropriate use of this test only increases the likelihood of false diagnoses being made, resulting in unnecessary dietary restrictions and decreased quality of life.”
“Food-specific IgG4 does not indicate (imminent) food allergy or intolerance, but rather a physiological response of the immune system after exposition to food components. Therefore, testing of IgG4 to foods is considered as irrelevant for the laboratory work-up of food allergy or intolerance and should not be performed in case of food related complaints”
When every major allergy and immunology body in the world has the same consensus and conclusions to IgG testing, along with the lack of scientific evidence, we really do not have an argument for the use of these tests. I could also show you statements from other countries like South Africa, German, UK, Singapore but I think you see the point, the consensus from the medical professionals (trained doctors specialising in food allergy and intolerance) is that these tests have absolutely no benefit when it comes to identifying food intolerances.
WHAT DO THE COMPANIES SAY:
Okay, first up lets clarify they are SELLING YOU A PRODUCT. Of course they are going to do what they can to convince you, you need it. They will site research that is poorly designed (yet tell you it is great but unless you know how to break down research it is hard for you to tell). Currently we do not have consistent, good quality evidence to support these tests. They are not a valid test that can reproduce accurate results and do not show food intolerance in an individual.
Many of these companies will also provide testimonials sharing stories of people who excluded foods and had improvement of symptoms. The first point here is a testimonial is not evidence, in fact testimonials can easily be made up by the company or individual. Secondly, reducing food variety significantly (as these tests generally end up forcing people to do) will in some individuals by coincidence make them feel better or make them lose weight (as they have less food choices thus eat less calories). This again is not scientific evidence.
HOW DO I TEST FOOD INTOLERANCE?
As we have discussed IgE testing for food allergies is beneficial and can be done through a Medical Doctor e.g an Immunologist or Allergist. For food intolerance the gold standard for diagnosis is through a process of elimination and re-introduction. This process should be done under the guidance of a medical doctor or qualified dietitian or nutrition professional who specialises in food intolerance (if said person offers IgG testing, walk away). Because food intolerances have varying degrees of sensitivity this process also lets us understand just how much of that food is required for an intolerance symptom to develop. Hydrogen breath tests are also available for lactose intolerance and are some times useful. However another simple way to diagnose lactose intolerance is through challenging. Drink a glass of milk - see what happens. Cheap, easy and can provide us with a dose-response result.
If someone suggests you do an IgG food intolerance test, either they are not evidence based and are trying to sell you something or giving them the benefit of the doubt they may not know (or have done the research yet) however someone shouldn’t recommend something they haven’t done the research on. Anyway, if there is someone who is suggesting you take one please point them to this article all references are below with links to the immunology boards across many countries above with further references.
Stapel SO, Asero R, Ballmer-Weber BK, Knol EF, Strobel S, Vieths S, Kleine-Tebbe J; EAACI Task Force.. Testing for IgG4 against foods is not recommended as a diagnostic tool: EAACI Task Force Report. Allergy. 2008 Jul;63(7):793-6. doi: 10.1111/j.1398-9995.2008.01705.
Tomicić S, Norrman G, Fälth-Magnusson K, Jenmalm MC, Devenney I, Böttcher MF. High levels of IgG4 antibodies to foods during infancy are associated with tolerance to corresponding foods later in life. Pediatr Allergy Immunol. 2009 Feb;20(1):35-41. doi: 10.1111/j.1399-3038.2008.00738.x.
Zeng Q, Dong SY, Wu LX, Li H, Sun ZJ, et al. (2013) Variable Food-Specific IgG Antibody Levels in Healthy and Symptomatic Chinese Adults. PLOS ONE 8(1): e53612.https://doi.org/10.1371/journal.pone.0053612
Johansson SG, Bieber T, Dahl R, Friedmann PS, Lanier BQ, Lockey RF, Motala C, Ortega Martell JA, Platts-Mills TA, Ring J, Thien F, Van Cauwenberge P, Williams HC. Revised nomenclature for allergy for global use: Report of the Nomenclature Review Committee of the World Allergy Organization, October 2003. J Allergy Clin Immunol. 2004 May;113(5):832-6.