Introduction
One of the more frustrating things that I experience as a Dietitian who works with people with food allergy is when people come to me with a lab report listing foods they are ‘allergic’ to—only for me to get a multi-page report that they paid $650-750 out of pocket for, and which measures IgG antibodies, not the IgE antibodies which are associated with food allergy.
Our body makes different types of antibodies, including IgA, IgG, IgM, and IgE. IgA antibodies are found in high concentrations in the respiratory passages and the GI tract. IgM antibodies are found in the blood and lymphatic system when fighting a new infection. IgE and IgG antibodies are covered below.
Immunoglobin E (IgE)
IgE antibodies are produced by the immune system and are normally found in very small amounts in the blood. When someone has an allergy, the body overreacts and produces high amounts of specific allergen IgE antibodies. When the IgE antibody binds with our mast cells, they release histamine which causes an allergic reaction, such as sneezing, itching, or difficulty breathing [1].
When people have very serious food allergies, they are advised to carry an Epipen in the event of anaphylaxis—a life-threatening reaction. Tests for food allergy always involve assessing the amount of IgE antibody response to a specific allergen, either by skin-scratch testing or a specific antigen IgE blood test.
Immunoglobin G (IgG)
IgG antibodies recognize foreign proteins, including those from infections and vaccines. Our body also produces IgG antibodies in response to foods; this is a normal response in a healthy immune system. These antibodies serve as a form of “memory” of exposure. Positive IgG antibodies to a food do NOT indicate a food allergy [2].
Food Sensitivity / Food Allergy Testing
If a person is referred to an Allergist, they will determine if IgE mediated antibodies are present. A Dietitian experienced with food allergy can help determine if symptoms underlie Oral Allergy Syndrome, where the body recognizes amino acid sequences in certain foods that are similar to tree pollens. Specific antigen IgE antibody testing is covered by provincial health insurance in Canada.
Alternative Food Sensitivity Testing – IgG
Some seek “food sensitivity testing” costing $650-$750, measuring how IgG binds to food in a petri dish. The problem is, IgG antibodies only indicate that the person’s body recognizes that food, not that they are allergic to it [2,3]. Only IgE antibodies assess true allergy.
Examples of IgG “Food Sensitivity” reports that do not diagnose food allergy.
MSAS and Applied Kinesiology
MSAS testing uses electrical currents on acupuncture points, while Applied Kinesiology Muscle Testing (unaffiliated with the science of Kinesiology) claims to find allergies based on arm strength. These are not scientifically validated methods for diagnosing food allergies.
Example of MSAS Food Sensitivity Testing Results report.
Food Intolerance
Food Intolerance is a non-IgE mediated sensitivity involving difficulty digesting foods, often due to an enzyme lack. Lactose Intolerance is caused by a lack of lactase. Histamine Intolerance occurs when the body lacks the enzyme diamine oxidase (DAO) to break down histamine from foods.
Final Thoughts
If you suspect a food allergy, seek a Dietitian and your doctor to rule out a genuine IgE-mediated allergy first. Don’t pay for tests that only measure exposure. Once identified, we can determine if you need to avoid the food entirely or simply adjust how often you eat it.
More Info?
I used to offer a Food Allergy/Food Sensitivity Package; however, most people would be seeking services based on IgG Food Sensitivity tests purchased through a naturpath. rather than IgE-mediated test results obtained through an allergist. I continue to support those diagnosed with IgE-mediated food allergies and, depending on the severity, will usually do so within the context of add-on services to the Comprehensive Dietary Package. You can learn about me here.
To your good health!
Joy
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References
- American Academy of Allergy, Asthma & Immunology. Immunoglobulin E (IgE) Definition. 2020. [https://www.aaaai.org/conditions-treatments/conditions-dictionary/immunoglobulin-e-(ige)]
- American College of Allergy, Asthma & Immunology. Can IgG blood testing check for delayed food allergies? 2020. [https://acaai.org/allergies/allergic-conditions/food-allergy/]
- Lavine E. Blood testing for sensitivity, allergy or intolerance to food. CMAJ. 2012 Apr 3;184(6):666-8. [https://doi.org/10.1503/cmaj.110026]
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Joy is a Registered Dietitian Nutritionist and owner of BetterByDesign Nutrition Ltd. She has a postgraduate degree in Human Nutrition, is a published mental health nutrition researcher, and has been supporting clients’ needs since 2008. Joy is licensed in BC, Alberta, and Ontario, and her areas of expertise range from routine health, chronic disease management, and digestive health to therapeutic diets. Joy is passionate about helping people feel better and believes that Nutrition is BetterByDesign©.