The term “allergy” is thrown around in common conversation way too freely and it is important to understand the difference between allergy, sensitivity, and intolerance.
Recently, I was invited to present to the allergy and immunology department at Sick Kids Hospital in Toronto. I was excited that medical doctors were interested in learning about the integrative approach on the subject of allergies.
Teaching at the hospital was an amazing learning experience and I wanted to share some key learnings with you.
Allergy: The Definition
Allergy is defined as strictly an ImmunoglobulinE-mediated (IgE) response (type 1 hypersensitivity) that usually causes immediate symptoms. For example, when an antigen (foreign molecule) is seen as a threat by the body, the immune system “flags” the antigen with an antibody (IgE) and then alerts the rest of the immune system to amount a response. The result is a release of histamine and other inflammatory chemicals. This is the most dangerous type of allergic response, as these reactions are what cause anaphylaxis and possible death. Common allergens are things like peanuts, shellfish, and eggs.
Alternately, sensitivity or intolerance is essentially any reaction in the body that cannot be attributed to an IgE response. An example of sensitivity is when people cannot tolerate MSG (monosodium glutamate), sometimes referred to as “Chinese Restaurant Syndrome.” While the inability to digest lactose (the milk sugar in dairy), might be referred to as an intolerance.
Although these are the “strict” definitions used by doctors, the terms are still loosely used; in fact, many scientific journals commonly refer to both IgE and IgG reactions as allergies.
IgE versus IgG
Doctors often hear the word “allergy” used by their patients, when in fact the patient may or may not actually be referring to an allergy, but a sensitivity or an IgG response. The patient might be indicating that a particular food causes a reaction.
Often patients are seeing a doctor about symptoms they think are food-allergy related, already having had an IgG food sensitivity test believing that this is the primary cause of their symptoms, when, in fact it may not be.
One of the biggest issues with IgG testing is that patients are not told about the limitations of the testing. Thus, people believe it is the answer to their woes, when in fact it is just part of the puzzle (more on this below).
The Challenge: Allergies Are Mediated By Different Parts of the Immune System
The current method for determining if an individual has allergies (IgE skin prick/scratch testing) has been shown to be an incomplete diagnostic tool. 1 For example, if a skin prick test is negative, the test is 95% predictive that the particular item in question is not an allergen. However, positive skin tests predict reaction 40% of the time, meaning that they might actually not have a reaction to that item.2 As you can see, skin prick testing tells us part of the story, but not the entire thing. IgE testing is one tool in the “tool box” and can give us an important piece of the puzzle, but not the whole answer.
As shown in the picture below, there are different branches of the immune system resulting in different immunoglobulin isotypes. Thus, symptoms experienced from these responses might require different testing methodology.
The Important Role Of The IgG Test
Enter the IgG test. This test is used mostly by naturopaths, nutritionists, and functional medicine practitioners. It can be completed by simply pricking the skin to get a sample of blood. Medical doctors do not trust this test as a valid measure, and in some ways, they are right not to.
There are a number of issues that compromise the acceptance of IgG testing by the medical establishment:
- The labs performing the test are not standardized from lab to lab. They maintain strict quality control and methodology within their respective labs; however, they do not use the same methodology.
- IgG reactions may or may not actually cause any symptoms.
The question becomes, does the IgG test show any benefits clinically when implemented in the right context? And the answer is, absolutely! Lets look at some of the evidence.
The Evidence Indicating Clinical Relevance of IgG Testing
In a study published in the journal Gut in 2004 that examined the relationship between diet and irritable bowel syndrome (IBS), one group of patients were given a “sham” diet, and the other group were given a modified elimination diet. The key point of our discussion here is that the modified elimination diet was determined by using IgG testing. If this test did not work, then you would see no difference between the two groups. The results proved otherwise. The group that followed the elimination diet experienced a 30% improvement of their IBS symptoms over the “sham” diet group.3
Other conditions where IgG-mediated responses have been shown to be involved are as follows:
- Autism 4
- Attention Deficit Disorder5
- Autoimmune and inflammatory disorders6
- Celiac disease7
- Crohn’s disease8
- Cystic Fibrosis9
- Food-hypersensitivity-induced atopic conditions12131415
- Irritable-bowel syndrome17
- Migraine headaches18
- Obesity and atherosclerosis19
- Rheumatoid arthritis 20
Labs that provide IgG Testing:
The Gold Standard
It is clear that that there are limitations with both IgE testing and IgG testing as they are both looking at a specific pathway. We must look to another way of determining allergies.
We must recognize that most people are exploring allergy testing because they are experiencing symptoms. The best tool in determining what is right and what is wrong for a patient is the ability to listen to their symptoms. The elimination diet is considered the gold standard in determining allergies because it looks at the symptoms of an individual, both on and off that questionable food. This methodology looks at the endpoint of physiological allergies, sensitivities, and intolerances; the endpoint being how the person feels.
For example, if a client comes to see me and tells me that when they eat wheat they get hives, but when they abstain they are symptom-free, why do IgE or IgG testing? Who cares if the response is IgG-mediated, IgE-mediated, or something else. Isn’t the ultimate goal symptom relief and results? Thus, we would eliminate the food immediately and see if it helped longterm. We might investigate IgE testing in the future to make sure the allergy is not life-threatening.
People are individuals and individuals require both different approaches and different treatments. Our current medical system does not take the individual into account. When people fall out of the medical scope of knowledge, they are sent on their way and told there is nothing wrong with them. Many of these people end up in my office searching for answers.
There is a growing movement of medical doctors who are open-minded and interested in learning about functional medicine. I have had many great conversations with these individuals at various functional medicine conferences. They, too, see the limitations of the current medical system and are studying to provide better care for their patients.
During my talk at Sick Kids Hospital my “holistic” approach was criticized as not being evidence-based. In my practice, the scientific evidence guides me, but the true evidence is when my clients get better. This to me is the best evidence of all.
- Annals Allergy. 1987;59(2):110-17
- Clark AT, Ewan PW. Interpretation of tests for nut allergy in one thousand patients in relation to allergy or tolerance. Clin Exp Allergy 33:1041-1045, 2003
- Atkinson W. Sheldon TA, Shaath N, Whorwell PJ. Food elimination based upon IgG antibodies in irritable bowel syndrome: a randomized controlled trial. Gut. 2004;53:1459-64.
- Heuer, L. et al. Reduced levels of immunoglobulin in children with autism correlates with behavioral symptoms. Autism research : official journal of the International Society for Autism Research 1, 275-283, doi:10.1002/aur.42 (2008).
- Pelsser, L. M. et al. Effects of a restricted elimination diet on the behaviour of children with attention-deficit hyperactivity disorder (INCA study): a randomised controlled trial. Lancet 377, 494-503, doi:10.1016/S0140-6736(10)62227-1 (2011).
- Ballow, M. The IgG molecule as a biological immune response modifier: mechanisms of action of intravenous immune serum globulin in autoimmune and inflammatory disorders. The Journal of allergy and clinical immunology 127, 315-323; quiz 324-315, doi:10.1016/j. jaci.2010.10.030 (2011).
- Husby, S., Foged, N., Oxelius, V. A. & Svehag, S. E. Serum IgG subclass antibodies to gliadin and other dietary antigens in children with coeliac disease. Clinical and experimental immunology 64, 526-535 (1986).
- Bentz, S. et al. Clinical relevance of IgG antibodies against food antigens in Crohn’s disease: a double-blind cross-over diet intervention study. Digestion 81, 252-264, doi:10.1159/000264649 (2010).
- Lucarelli, S. et al. Food allergy in cystic fibrosis. Minerva pediatrica 46, 543-548 (1994).
- Haroun, M. & M, M. E.-S. Measurement of IgG levels can serve as a biomarker in newly diagnosed diabetic children. Journal of clinical biochemistry and nutrition 40, 56-61, doi:10.3164/jcbn.40.56 (2007).
- Egger, J., Carter, C. M., Soothill, J. F. & Wilson, J. Oligoantigenic diet treatment of children with epilepsy and migraine. The Journal of pediatrics 114, 51-58 (1989).
- Awazuhara, H., Kawai, H. & Maruchi, N. Major allergens in soybean and clinical significance of IgG4 antibodies investigated by IgE- and IgG4-immunoblotting with sera from soybean- sensitive patients. Clinical and experimental allergy : journal of the British Society for Allergy and Clinical Immunology 27, 325-332 (1997).
- el Rafei, A., Peters, S. M., Harris, N. & Bellanti, J. A. Diagnostic value of IgG4 measurements in patients with food allergy. Annals of allergy 62, 94-99 (1989).
- Nakagawa, T. et al. [Clinical significance of IgG4 antibody determination in children against egg white, milk, soybean and Dermatophagoides farinae]. Arerugi = [Allergy] 41, 1694-1704 (1992).
- Hofman, T. IgE and IgG antibodies in children with food allergy. Rocz Akad Med Bialymst 40, 468-473 (1995).
- van der Woude, F. J. et al. Do food antigens play a role in the pathogenesis of some cases of human glomerulonephritis? Clinical and experimental immunology 51, 587-594 (1983).
- Zar, S., Mincher, L., Benson, M. J. & Kumar, D. Food-specific IgG4 antibody-guided exclusion diet improves symptoms and rectal compliance in irritable bowel syndrome. Scandinavian journal of gastroenterology 40, 800-807, doi:10.1080/00365520510015593 (2005).
- Alpay, K. et al. Diet restriction in migraine, based on IgG against foods: a clinical double- blind, randomised, cross-over trial. Cephalalgia : an international journal of headache 30, 829- 837, doi:10.1177/0333102410361404 (2010).
- Wilders-Truschnig, M. et al. IgG antibodies against food antigens are correlated with inflammation and intima media thickness in obese juveniles. Experimental and clinical endocrinology & diabetes : official journal, German Society of Endocrinology [and] German Diabetes Association 116, 241-245, doi:10.1055/s-2007-993165 (2008).
- Hvatum, M., Kanerud, L., Hallgren, R. & Brandtzaeg, P. The gut-joint axis: cross reactive food antibodies in rheumatoid arthritis. Gut 55, 1240-1247, doi:10.1136/gut.2005.076901 (2006).