Should I do a food sensitivity test, and will it help me diagnose my gut issues?
Should I do a food sensitivity test, and will it help me diagnose my gut issues?
November 10, 2021 by Allie Buxton, edited by Lesley Seto MSc.A, RD
About 25% of people experience an adverse reaction to food at some point in their life. Identifying the cause of the reaction and managing symptoms can often be confusing and overwhelming. Food sensitivity tests have become a popular tool, promising to help people identify problematic foods. But do these tests really work, and will they help you manage your symptoms?
What are food sensitivity tests?
You might have seen these tests advertised on social media, in your Google searches, encouraged by some health practitioners, or even promoted at the same labs you get bloodwork done. Like food allergy testing, most food sensitivity tests use a blood draw to test for the presence of a specific antibody. You may also see food sensitivity tests that use saliva or hair instead of a blood sample.
Our bodies produce antibodies as part of an immune response to protect us from a perceived harmful substance. There are a few different types of antibodies produced by the body. During an allergic response, the body produces immunoglobulin E (IgE) when it detects proteins from food the person is allergic to. Food allergy tests will analyze the amount of food-specific IgE antibodies present in a blood sample; an elevated IgE level is said to be a positive test.
Food sensitivity tests are built around the same principle but test for immunoglobulin G (IgG). It’s important to recognize that food allergies and food sensitivities are not the same things. Food allergies result in an immediate immune reaction whereas food sensitivities cause a delayed response (learn more about the differences here). The mechanism of food sensitivities is not well understood. Although the immune system is involved, IgE antibodies are not associated with the condition and there is currently no body of evidence to support the use of IgG antibodies to diagnose food sensitivities.
What is immunoglobulin G (IgG)?
Food sensitivity tests claim to identify food intolerances or sensitivities by measuring IgG antibody levels for different foods. While IgG antibodies are produced in response to food, they are actually a marker of exposure to a food and not a marker of symptoms of intolerance or sensitivity. In fact, IgG is the most common type of antibody in the blood, representing about 75% of circulating antibodies. Elevated IgG levels don’t necessarily mean you’re sensitive to a food, but more likely that you’ve eaten it recently or frequently.
What’s the problem with food sensitivity tests?
Because IgG is an exposure indicator, most people’s test results come back showing elevated levels for commonly consumed foods. Often this includes long lists of foods, including sensitivity to gluten, dairy, soy, and certain vegetables and fruits. Getting these results usually ends in two scenarios:
People feel overwhelmed by the long list of foods they are “sensitive to” and shouldn’t eat. They feel hopeless and like they have no control over their health.
People stop eating foods on the list and try to follow a restrictive diet that leaves little joy in eating and can lead to nutrient deficiencies.
On top of this, the tests are also quite expensive. Most food sensitivity tests range from $100 to $500 and often provide little to no useful information, leaving you to continue to struggle with the digestive symptoms you’re experiencing.
What should I do instead to identify possible food sensitivities?
When you’ve been experiencing food challenges for a long time without a solution, it can be frustrating. If you find yourself suspecting a food sensitivity, rather than restricting all sorts of food at once, it is better to gradually restrict and reintroduce foods to determine how your body responds.
You can start by keeping a detailed food and symptom log to identify potentially problematic foods. Bringing this to your family doctor or to a Registered Dietitian can help you identify common trigger foods or meals. They can also help you work through the root cause of your sensitivities and set you up with a diet that will alleviate your symptoms while ensuring you don’t feel restricted or at risk of nutrient deficiencies.
So, what about food allergy tests?
Unlike IgG used in food sensitivity tests, the IgE antibody tested for in food allergy tests is recognized as the allergy-related antibody. However, some people can still produce IgE antibodies in response to a food and not have an allergy to that food. Further, these tests cannot predict the severity of a food allergy. That’s why a positive IgE allergy test alone is not considered a diagnosis of a food allergy. Your doctor will also perform a physical exam, ask you questions about your symptoms, family medical history, and may also refer you to an allergist for a skin prick test or oral food challenge to confirm if you have a food allergy.
Navigating the world of food sensitivities can be overwhelming and frustrating. If you have any questions or concerns about food sensitivities, food allergies, or testing, leave a comment below or book a discovery call with Lesley.