A recent CBC Marketplace article and investigation has shed a negative light on IgG food sensitivity testing. It proposes that nutritional IgG antibodies are "not related to the immune system" and do not play a role in various health concerns. There are many logical and common sense "holes" in the arguments suggested in this article. This post will shed some light on some of the most obvious errors and misinformation.
The role of Immunoglobulin G or IgG in disease (and specifically autoimmune disease) is extremely well researched and accepted in the conventional medical world. A simple PubMed database search using IgG and Autoimmunity will provide numerous conventional medical studies in peer reviewed journals outline associations between Immunoglobulin G and various diseases. One simple and significant example can be shown in the two studies below regarding Type I diabetes in children.
There are many more examples of the association between various infectious and food IgG antibodies and various disease processes and pathologies.
The article suggests...
...experts, including the Canadian Society of Allergy and Clinical Immunology (CSACI), call IgG tests for food sensitivities "unvalidated," and more than two dozen organizations warn about the misuse of such tests.
ELISA testing (Enzyme Linked Immuno-sorbent Assay) is a medically validated and heavily used diagnostic test procedure in the conventional medical system often used to diagnose various medical conditions such as viral diseases (Hepatitis, Epstein Barr Virus, Parvo, and many others) and also IgA auto-antibodies for nutritional related diseases such as Celiac Disease. By suggesting the test procedure is "un-validated" they are essentially saying their own testing procedure is un-validated.
The article suggests...
...the testing will show IgG antibodies to foods that you have been eating or exposed to...
Then why do foods that we eat regularly NOT show up on the test results. The testing shows what we have been eating THAT OUR IMMUNE SYSTEM RECOGNIZES AS reactive. If we aren’t reactive to a food and we eat it. It won’t show an elevated IgG level to that food. An IgG immunoglobulin is produced when a specific type of white blood cell called a T-cell binds to an ALLERGEN. It then combines with a plasma cell or B cell to produce IgG immunoglobulins AGAINST the Allergen. This is an ALLERGIC REACTION to the antigen. Those who suggest this isn't an allergy are obviously incorrect. It's just a different type of allergy. Please read the following article for further explanation and clarification on this topic.
The following ELISA test was done for a patient of mine some time ago. This test result shows very clear IgG reactions to Dairy products, Eggs, Bananas, Pineapple, Almonds and Sesame. It also shows IgA reactions to Dairy products. The argument in the CBC article suggests that the IgG results just show what you have been eating. This would suggest that this patient didn't eat any meat proteins (which she did frequently), other fruits such as apples, citrus, strawberries, etc. (which she did frequently), or any bread products, other nuts aside from almonds, beans, etc. (which she did frequently).
I have done hundreds of tests and every test will show many foods the patients are eating regularly, but not showing IgG or IgA antibody responses to. If the argument in the article was true, this would not be the case.
The article suggests...
...Sensitivities or intolerances, on the other hand, ARE NOT RELATED TO THE IMMUNE SYSTEM and often take hours, if not days, to take effect — and are therefore very difficult to diagnose.
Immunoglobulin G or IgG, also known as antibodies, are glycoprotein molecules produced by plasma cells (white blood cells). They act as a critical part of the immune response by specifically recognizing and binding to particular antigens, such as bacteria or viruses, and aiding in their destruction. By medical definition they aren’t just related to the immune system, they ARE PART OF the immune system. The claim made that they aren’t associated with immunity goes against everything in basic immunological science.
The suggestion that they often take hours to days to effect people is absolutely true. This is the key reason why people struggle with these types of food issues. When they look for reactions to foods, they look to see what happens immediately when they eat the food. They don't think to look at what happens to their bodies and symptomology for hours and days after ingesting the foods. This is what makes IgG testing helpful and beneficial for patients, it can help identify these delayed reactions.
The article suggests... (regarding the patient example in the article)
...patient had tracked what she was eating. Yet both tests reported intolerances to foods she regularly consumed, with absolutely no adverse reactions. For example, patient had a smoothie, which included flax seeds, for breakfast daily. Yet both tests suggested patient is intolerant to flax. She also ate vegetable soup — containing barley, kidney beans and corn — without problem. Both IgG tests again claimed patient is intolerant to these foods.
When the patient in the example ate the foods, she was looking for reactions to those foods immediately when she ate them. As the article states the IgG reactions can take hours to days to reach the system and this delay could result in a delayed reaction to the foods. If she ate those foods and had an adverse reaction the following week, she would be unlikely to correlate the food to the symptom.
Also, in order for an IgG food antibody to elicit a reaction, there has to be a tissue in the body for it to react against in order to cause a symptom in that tissue (molecular mimicry). If she produces an IgG antibody against a food, but does not have a mimicking tissue in her body, she may not have any symptoms when she eats that food. An IgG antibody to a food can go through circulation in the body and not cause any issues much the same way as an IgG vaccine can this.
You may have 10 different circulating IgG food antibodies in circulation, but it may only be 1 or 2 of them that cause cross reactions. This study reference above doesn’t take into account the delayed nature of response with IgG food antibodies, nor does it take into account possible tissue cross reactions with these food antibodies. (molecular mimicry)
The article suggests...
...The reports being generated by the IgG test taken ... and countless others are being grossly misinterpreted, critics say.
Unfortunately, this is accurate in many cases. Unless the practitioner has thorough understanding of the dynamics of how IgG antibodies are produced, how long they can stay in the system and how they can interact with tissues in the body, misinterpretation of the results can happen easily.
The key points often NOT taken into account when interpreting the results are
Molecular mimicry - Only IgG antibodies which recognize a tissue in the body as being similar to the antigen which produced the IgG antibody, will be likely to cause a noticeable or apparent physical reaction in the patient. Other IgG antibodies may NOT elicit any reactions.
IgG ProductionDynamics- An IgG antibody can take up two weeks from exposure to reach a peak antibody load in the blood stream (much the same way as vaccines antibodies are produced) This means an IgG related food might take several days to elicit a reaction in the body and this reaction may not be apparent to the individual eating the food.
The following articles can help explain some of the technical aspects to IgG and IgA food allergies.