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Are food sensitivity tests helpful or harmful?

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Symptoms of Irritable Bowel Syndrome (IBS) and a stressed stomach include abdominal pain, bloating, constipation and diarrhea. These symptoms can be irritating, embarrassing, anxiety provoking, and can have a significant impact on quality of life. Aside from the common cold, symptoms of IBS are the second most common reason to miss work or school. In individuals with an eating disorder, symptoms of IBS or digestive upset are even more common than for those in the general population.

A diagnosis of IBS in and of itself is a frustrating diagnosis. It’s a diagnosis of exclusion, meaning you have worked with a doctor to rule out conditions such as crohn’s disease, celiac disease, or a stomach ulcer, yet you still have symptoms. A diagnosis of IBS often brings relief in that many serious conditions have been ruled out, but frustration in that usually very few recommendations are given in terms of how to improve or manage your symptoms. It’s common for individuals with digestive upset to feel so desperate for an answer that they are willing to try anything.

An option that is gaining popularity online and among alternative health care practitioners is IgG food intolerance testing. Before considering this test, it’s important to educate yourself on the science behind it. The current consensus among allergy professionals is that IgG testing is not validated and has risks associated with it.

What is a food intolerance?

Food intolerances are a real thing that can have a significant impact on one’s quality of life. They can cause symptoms of IBS, along with skin rashes and joint pain. Food intolerances, however, are very different from food allergies. A food allergy is an immune-system response that can cause anaphylaxis and an increase in IgE antibodies in the blood. A food intolerance causes symptoms and discomfort but usually does not cause harm or damage to your body and does not trigger an immune-system response.

How can we test for a food intolerance?

Unfortunately, an accurate and validated test for food intolerances does not currently exist. The only way to truly determine if you have a food intolerance is to complete an elimination diet under the supervision of a registered dietitian who can help you pinpoint foods that may be triggering your symptoms. In an elimination diet, it is important to remove certain foods to see if symptoms improve, and equally important to reintroduce foods to see if symptoms return and to ensure you are not needlessly restricting your food routine. Embarking on an elimination diet to determine if you have a food intolerance is a long process that requires patience and guidance.

Then what is IgG testing?

Immunoglobin G (IgG) is thought to be a marker of exposure to foods, and a measure of our tolerance to them. This means that individuals typically have the highest IgG levels for foods that they eat regularly. It is completely normal and healthy for all individuals to have positive IgG test results. Somehow this test has come to be marketed as a way to detect food intolerances, when it actually detects our tolerance to foods.

But if there isn’t a good test out there, can’t I at least try the IgG test?

The IgG test is very expensive ($300-700) and, according to the Canadian Society for Allergy and Clinical Immunology, not a valid way to detect for food intolerances. Instead, this testing often results in individuals following needlessly restrictive diets. For someone with an eating disorder, it is very likely that an IgG test will be triggering. The test results can cause significant fear and anxiety around specific foods when there truly is no benefit to excluding these foods from your food routine.

If you experience symptoms of IBS or a stressed stomach, it’s important to create a support team that includes a doctor, a dietitian, and a counsellor to help you determine your individual triggers while still including a wide range of foods and preserving a healthy relationship with food.

Blog post written by Lindzie O’Reilly, MAN, Registered Dietitian, Student Health Services, University of Guelph.