We are a society that is struggling with digestive woes. From bloating, to gas, to indigestion, to functional disorders like IBS, optimizing our digestive health has been a big focus for many! And I get it – digestive trouble can be frustrating! But before you consider food sensitivity tests or elimination diets, consider the science behind some of these tests, and consider working with a dietitian instead. Today we’re diving into allergy testing, food sensitivity tests, and why the answers you’re looking for might not be in a testing kit…
Let’s Start With Laying Some Basic Ground Work So We’re All On The Same Page…
There’s a lot of language thrown around when it comes to food and our eating patterns. This language gets particularly complex when we start exploring the many reasons why we may be eliminating food from our diets. It would probably be helpful to start off by defining some of these terms and sharing the science behind them. To keep it simple (we could talk for days on this topic) we’ll stick to three key definitions when it comes to adverse food reactions – an allergy, intolerance, or food sensitivity.
Food Allergy: this is an Immune Activated response that occurs after exposure to a particular food. This response occurs reproducibly (meaning every time you eat the particular food, an immune response occurs). These responses are associated with immunologic activity that is IgE mediated or non-IgE mediated (cell mediated). Common food allergens include: milk, eggs, peanuts, tree nuts, shellfish, fish, soy, sesame seed, and wheat.
Super Quick Very Basic Immunology Overview:
So, what are all these letters and big words I’m throwing around? An IgE immunoglobulin is an antibody (a blood protein) produced by your immune system. These antibodies react to antigens, also called allergens– basically just something the body recognizes as ‘foreign’ that is causing you to have an immune reaction. An IgE-mediated allergic reaction means that these IgE antibodies cause an immediate inflammatory response to what the body has identified as an allergen. This may present as a short-term skin reaction, gastrointestinal disturbances, and/or respiratory problems.It may also look like hives, swelling, itching, rash, congestion, wheezing, nausea, cramping, diarrhea, or more serious issues such as anaphylaxis. When you think of a classic food allergic response, you’re thinking of an IgE-mediated allergic response.
A cell-mediated allergic reaction (or non IgE-mediated reaction), is an immune response that involves T-cells (yet another immune cell – our bodies are complex and amazing!) and is characterized by a delayed response. A person with this type of allergy may experience severe vomiting or diarrhea up to 2-3 hours after eating a food. These allergies can be harder to diagnose, and I’ll leave it at that for the purpose of this discussion.
Okay, back to our definitions. We’ve described an allergy, let’s move on to an intolerance…
Food Intolerance: this is not an immune reaction to a food, and symptoms are primarily in the gastrointestinal tract. An intolerance results from an inability to digest certain foods. A common example of this is lactose intolerance, where certain individuals cannot produce enough of the enzyme lactase. Lactase is responsible for digesting lactose (the sugar found in milk) in the gut. As a result, the lactose isn’t digested properly and can cause symptoms such as gas and bloating and can be very uncomfortable.
Food Sensitivity: this is a newer term that has popped up partly in thanks to marketing and the rise of the health & wellness industry. It is a term that is thrown around rather loosely, and it has no clear definition. It’s also important to note that at this time, a food sensitivity is not a specific medical diagnosis, meaning we don’t have any reliable, accurate way of determining this. However, that doesn’t mean that your concerns about certain foods aren’t valid – keep reading!
The Biggest Difference Between Food Allergies And Food Sensitivities…
Allergy Testing: there are multiple tools that must be utilized to properly and reliably diagnose a food allergy. This includes collecting comprehensive medical history and physical exams (done by a doctor, and preferably an allergist) followed by allergy tests. The tests are selected based on a persons’ history, to confirm the potential diagnosis. These tests may include blood tests or skin prick tests to measure IgE antibody levels. Evidence of these IgE antibodies in the blood, in combination with a detailed medical history and discussions with your health care team, can serve to diagnose food allergies.
To fully understand the differences between allergies and sensitivities (and why food sensitivity testing might be a waste of your money), we need to look at those antibodies again.
Food Sensitivity Tests: many alternative or complimentary healthcare providers offer food sensitivity testing. Heck, there are even kits you can buy now where you mail in a blood sample and a company can mail you back your sensitivity results! These test results often include long lists of foods (and often foods regularly included in many of our diets) that you are “sensitive” to. Often, it is recommended that you eliminate or minimize these foods in your diet to alleviate symptoms including but not limited to: brain fog, fatigue, headaches, acne, and even anxiety or irritability. Rather than looking for IgE antibodies in the blood, these tests measure the levels of IgG antibodies. They’re both antibodies, so this should be fine, right? Not quite.
Here’s where the important difference lies: while IgE antibodies cause an immune-mediated immediate inflammatory response (A.K.A. an allergic reaction), IgG antibodies have been shown to be a marker of food exposure and tolerance. While the creation of IgG antibodies are still indicative of an immune response, it is a normal response associated with exposure to foods, and often repeated exposure to foods. This means that you may have higher IgG levels for foods that you commonly eat! The presence of IgG antibodies is not a marker of hypersensitivity and adverse reaction (as it is with IgE antibodies), but rather it indicates a physiological response to food exposure. Which is why IgG food sensitivity tests often return a long list of common foods that you may be “sensitive” to – it’s a marker of exposure RATHER than a marker of allergy or harmful sensitivity.
The Canadian Society of Allergy and Clinical Immunology is so concerned about these tests leading consumers astray, that they have issued a position statement on IgG testing, stating that as of now, there is no body of research to support the use of IgG testing in diagnosing adverse food reactions or predicting future food reactions. As IgG is a marker of exposure and potentially tolerance to food, these markers are expected in normal, healthy adults and children.There are also safety risks associated with marketing misinformation to consumers. People with serious IgE-mediated food allergies (anaphylactic responses), may have low IgG levels for that same allergen, meaning that a potentially serious and very real food allergy is being missed in favor of 20 other food sensitivities indicated by this test.
Here’s Where The Dietitian Gets Real Concerned…
Not only are you potentially wasting hundreds of dollars on these food sensitivity tests (which, if you’re like me, that’s money better spent on tacos and I don’t know…rent?), you’re also opening yourself up to unnecessary stress and anxiety around food! Ironic that a food sensitivity test used to find the cause of your anxiety or irritability only sends you back a huge list of foods you regularly eat, and then recommends you eliminate these foods. This means you are now spending more time stressing about all of your dietary restrictions and paying more money for egg-free, dairy-free, everything-free alternatives. Totally anxiety-easing…. right? This is how diet culture sneaks in as “wellness”.
All joking aside, my main concern with these food sensitivity tests is the totally unnecessary restrictive eating patterns that they may cause. I can’t even count the number of people I’ve encountered who are trying to navigate extremely restrictive diets due to a food sensitivity test. Trying to create a sustainable meal pattern when you can’t have eggs, milk, apples, pineapple, cane sugar, coffee, soy beans, wheat, and onions (just to randomly pick a few of the top food sensitivities often listed) is not only challenging, but it can feel defeating. Not to mention the food fear and anxiety that these tests cause! It’s a slippery slope into disordered eating territory and can create an unhealthy obsession not only with foods but with obsessively tracking our body reactions. We become hyper aware of what we’re eating and attribute every symptom we experience to these “trigger foods” – which may be totally unfounded. It makes me cringe.
Before I sign off on this one, let me say one more very important thing. Science matters, and it’s what I will always base my recommendations and suggestions on (after all, we don’t call it evidenced-based practice for nothing), but YOU also matter. And your concerns are valid and deserve to be heard. We live in a complex world with an even more complex food system which means that we have different ailments and concerns than we may have had in the past. And if you’re concerned about certain foods, or you’re struggling with gut issues, there are qualified people (read: dietitians) who use evidence-based methods to solve digestive woes and help you feel your healthiest. So please, if you have concerns, see a dietitian and commit to working with them before you cut out 50% of the foods you love in one fell swoop. Eating food is supposed to be a joyful thing, don’t let some unsupported sensitivity test suck the fun out of food.
American Academy of Allergy Asthma & Immunology. (2018). The myth of IgG food panel testing | AAAAI. Retrieved from https://www.aaaai.org/conditions-and-treatments/library/allergy-library/IgG-food-test
American Academy of Allergy Asthma & Immunology. (2018). Allergist / Immunologists: Specialized Skills | AAAAI. Retrieved from https://www.aaaai.org/about-aaaai/allergist-immunologists-specialized-skills
Carr, S., Chan, E., Lavine, E., & Moote, W. (2012). CSACI Position statement on the testing of food-specific IgG. Allergy, Asthma & Clinical Immunology, 8(1), 12.
Food Allergy Canada. (2018). FPIES. Retrieved from https://foodallergycanada.ca/about-allergies/related-conditions/fpies
Gocki, J., & Bartuzi, Z. (2016). Role of immunoglobulin G antibodies in diagnosis of food allergy. Advances in Dermatology and Allergology/Postȩpy Dermatologii i Alergologii, 33(4), 253.
Nordqvist, C. (2017, December 20). Food Intolerance: Causes, types, symptoms, and diagnosis. Retrieved from https://www.medicalnewstoday.com/articles/263965.phpSpergel, J. M. (2006). Nonimmunoglobulin e-mediated immune reactions to foods. Allergy, Asthma & Clinical Immunology, 2(2), 78.