Understanding Food Allergy and Food Sensitivity (IgA vs IgG vs IgE reactions)

Super Healthy Kids

With a surge in recent advertising of gluten and dairy free foods, so many people are now wondering about food allergies. They wonder if they have food allergies, and if they too should be avoiding certain foods to improve their health. This can be a confusing topic, and this article is designed to help you understand the difference between allergic food reaction and food sensitivity or intolerance and whether you might benefit from food sensitivity testing.

To answer this question, it is helpful to understand a little about our IgA, IgE, and IgG immune responses. IgA, IgE and IgE refer to immunoglobulins, or “antibodies.”  These antibodies are part of our immune system, and are produced in response to things we come in contact with on a daily basis. Our bodies make antibodies to foreign substances like bacteria and viral cells, but can also respond to foods, dust, dander, and pollen. Antibodies help the body mount an immune system response (“fight”) against foreign invaders.

IgA and IgG reactions are known as delayed response reactions, that include food sensitivities, where IgE responses are immediate and are considered a true food allergy. IgA and IgG reactions may not happen immediately, but can take hours to days to show up in your skin or intestines, and cause symptoms related to inflammation like headaches, fatigue, brain fog, or joint pain. People with food intolerance may experience digestive upset like nausea, constipation, or diarrhea, or skin itching and rashes including conditions like eczema and psoriasis.

IgE Reactions

IgE immediate hypersensitivity reactions are characterized by the hives, and throat swelling that accompany anaphylactic reactions some people experience when exposed to certain foods.  Other symptoms can include wheezing, coughing, a runny nose, vomiting, swelling of the lips or tongue, tearing or redness of the eyes, or even a weak pulse and loss of consciousness.  Common foods that trigger IgE reactions are peanuts, shellfish, egg, dairy products, soy, tree nuts, wheat and fish.

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IgA Reactions

IgA immunoglobulins are present in our mucus membranes and helps us fight bacteria and viruses. IgA increases in response to foods when the foods we eat cause inflammation, and in response to stress, disease, or alcohol.

IgG Reactions

An IgG reaction to food proteins suggests tolerance related to immune cell reaction. Repeated exposure, inflammation, and immune reactivity contribute to sensitivity and high IgG in response to food proteins.

Testing for Food Allergy and Sensitivities

We test for IgE allergic reactions with skin prick or patch testing as well as blood testing to know what foods and other allergens must be avoided and when an Epi-pen is an appropriate prescription.

While you can test IgG and IgA for rood reaction, this is not diagnostic of hypersensitivity or allergy, but sensitivity and intolerance, as well as inflammation. While blood testing is available for food sensitivity reactions, these tests are controversial as the results are commonly not reproducible and are not as reliable as elimination diets for uncovering food sensitivity.

What About Celiac Disease?

If it seems like everyone has a gluten intolerance these days, you may find you are just gluten sensitive through IgA and IgG testing. If you are not diagnosed with celiac disease, you may be gluten sensitive and not gluten intolerant. Those who truly have an allergy to gluten have celiac disease, which is caused by an autoimmune response to proteins found in wheat and some other grains, and harms the cells of your small intestine. Testing for celiac disease is done with a blood sample looking for more specific immune reaction to gluten and gliadin and confirmed with a biopsy of the small intestine. For more information about wheat allergy vs. celiac disease please see our article Should Your Child Avoid Gluten?

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Why would you consider testing for IgA and IgG food sensitivities if the tests are not 100% reliable?

  • You like to see laboratory data with recommendations for how to proceed.
  • Your friend or family member did the testing and it helped them to feel better.
  • An elimination diet may not work for you for one of these reasons:
    • They are time consuming and can take months to go through the process of eliminating and then challenging foods.
    • You have a picky/growing kid who already avoids some foods. You don’t want to restrict calories, or risk food aversion, or tension that can go along with an elimination diet.
    • You are busy, enjoy eating out, or don’t have time to cook, and have limited time for the shopping and meal planning that is required to follow a restricted.

If food sensitivity testing seems like it might be a good fit for you, or if you prefer to try an elimination challenge diet to address your symptoms, see a Naturopathic Doctor to help you navigate the world of food reactions.  You can also check out our e-guide: How to do an elimination/challenge diet (E-Book)

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Meghan Kemnec
Meghan Kemnec

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