I cook for a group of friends every Monday night and they have definitely challenged my creativity in the kitchen. The menu is gluten-, dairy-, peanut- and egg-free! With the exception of a peanut allergy, these diet restrictions are based on food sensitivities or intolerances. While food allergies are relatively well understood in terms of cause, diagnosis and treatment, food sensitivities and intolerances are not as clear and testing isn’t standardized. This can result in misdiagnoses with serious health consequences.

Food Allergies, Intolerances, (hyper)sensitivities… oh my!

The terminology surrounding adverse reactions to food is enough to make one’s head spin. Let’s break these down into manageable terms.

·       Food allergy – Allergies involve an Immunoglobin E (IgE)-mediated immune response to a protein in food. What sets an allergy apart from other food reactions is that it involves the immune system (remember this key point for later). Even a trace amount of the food can cause a potentially life-threatening reaction and symptoms are typically immediate (e.g. wheezing, hives, swelling, vomiting, diarrhea, rapid heart rate, anaphylaxis). Canada considers 10 foods to be Priority Allergens.

·       Food intolerance – Intolerances occur in the digestive tract and do not involve the immune system. They may be due to an enzyme deficiency, as is the case in lactose intolerance, or a reaction to a food additive or naturally occurring chemical in food. They may have a ‘threshold level’ where a small amount of food has no effect, but larger amounts do. Symptoms are not life threatening and are often delayed, making them harder to diagnose (e.g. bloating, gas, abdominal pain, diarrhea, etc.).

·       Food (hyper)sensitivity – There is no universally accepted definition for a food sensitivity (some may use the term hypersensitivity). They also do not involve the immune system and symptoms overlap with those of food intolerances, spanning digestive issues, ‘brain-fog’, headaches, lethargy, etc. To make things trickier, the terms intolerance and food sensitivity are often used interchangeably, likely because sensitives aren’t well understood.

Why is it important to understand the differences among food allergies, intolerances and sensitivities? Because how we diagnose and treat these reactions differs depending on the condition and this can have serious health implications.

Testing 1, 2, 3

If you have a food allergy, you’ve likely been to an allergist and had a skin-prick test, blood test or oral food challenge[. These are all proven testing methods that consider factors involved in the immune system. Every allergist and lab in Canada uses the same methods to conduct these tests. Based on the results, combined with your history of reaction, a reliable diagnosis can be made and treatment is strict elimination of the problem food.

When it comes to food intolerance's and sensitivities, matters aren’t so simple. The testing methods used for allergies don’t work for intolerance's and sensitivities because they don’t involve the immune system. Unfortunately, there are many tests available that are not clinically proven, leading to unnecessary restriction. The most common of these is the Immunoglobulin G (IgG) test.

IgG testing for food sensitivities

An IgG test is the most popular alternative food sensitivity test. However, there are a few problems with using IgG to test for intolerance's.

1.     IgG involves the immune system and we learned above that food sensitivities don’t involve the immune system.

2.     The amount of IgG in the blood typically increases with exposure to a food. In other words, if you’ve been eating a lot of wheat, you will have more IgG for wheat in your blood. This may be why wheat, dairy and eggs are often eliminated after IgG testing.

3.     Finally, there is no standardized method for testing IgG. This means that results might be different depending on which lab or practitioner does the test.

Taken together, IgG is not a reliable test for detecting food intolerances or sensitivities. This is only one of many alternative testing methods available, and, unfortunately other testing methods don’t seem to be any more reliable. If you are wondering about another alternative testing method, see this great articlefrom the Australian Society of Clinical Immunology and Allergies.

Food intolerances and sensitivities are not easy to live with; food is an essential part of life and we want to enjoy it without discomfort. However, using an unreliable test can lead to eliminating foods that don’t need to be eliminated. The most serious consequence of this is nutrient deficiency (especially risky for children and adolescents) but can also include increased stress, difficulty getting a real diagnosis and overall decreased quality of life.

Food hurts – what should you do?

At this point, you think that something you are eating is causing pain and there is no reliable test to determine what it is. Where does this leave you? Here are some practical steps to help determine if it really is a food sensitivity.

·       Take a vacation  from internet research – there is no limit to what you will find on the internet and there will be many different opinions. Consider a break from the internet so that you can tune into what your body is telling you, rather than what different health and lifestyle bloggers, wellness coaches and alternative practitioners are telling you.

·       Make an observation envelope – it can be tempting to blame a particular food and eliminate it based on how you feel after a meal but committing to a period of observation before eliminating foods could prove useful. Whenever you feel physical symptoms, think back to what you ate and write it down on a slip of paper. Stick this in an envelope and don’t look at it again until the end of your observation time (e.g. two weeks). At the end of the observation period, look for any trends.

·       Consider non-food triggers – it is important to consider that factors other than food may be affecting you. We like to point the finger at food because it is in our ability to control. However, hormones, stress, anxiety and many other factors can trigger ill feelings. What other factors in your life could be creating sensitivities? Write these down for your observation envelope as well.

·       Eat regular, balanced meals and snacks –structure your eating during your observation period. Skipping meals and eating large amounts when famished can be hard on your digestive system. Likewise, a meal that is mostly vegetables, in particular raw veggies, or with a large amount of pulses can cause digestive woes.

·       Work with a dietitian – I highly recommend a registered dietitian who specializes in food sensitivities. It can be incredibly helpful to have an objective source to systematically work through triggers and diet modifications.

What about an elimination diet? You’ll have to stick around for Part Two of Food: Friend or Foe? Is an elimination diet right for you?

Food sensitivity is a very broad topic and we’ve only brushed the surface. These Albertan dietitians have a wealth of detailed information to help you.


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Kristina Isaac, RD.

Registered Dietitian

Kristina (BSc, RD) is a registered dietitian and blogger for Nourish Move Thrive. She enjoys finding creative, fun and simple ways to communicate the science of nutrition.

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