from left to right - hazelnuts, shrimp, soy beans, eggs, fish, peanuts, milk, flour, seafood

Ultimate Guide To Food Allergies : Answering Your Frequently Asked Questions

Over 3 million Canadians are affected by food allergy, that’s 7.5% of the population. The impact of food allergy is far greater, with an estimated 50% of households being either directly or indirectly affected by food allergy.  Chances are you have a food allergy or know someone who is living with one.

As registered dietitians – we see many people suffering from food allergies and intolerance in our practice.  Our allergy dietitians are dedicated to educating on up-to-date research.  This may include helping you get clarity on your symptoms, fight misinformation, prevent food allergy reactions, learn to cook and eat in a new way, and get all the nutrition you need despite the dietary restrictions.

What are the differences between food allergy and intolerance?

Food allergy is the reaction that involves your immune system.  Your immune system is reacting to a food protein or the allergen that you have ingested, and symptoms can range from rash, hives, vomiting, diarrhea and can lead to anaphylaxis, which can be a life-threatening condition. 


There are many different types of food allergies which one of the reasons why you may be getting conflicting information on how to best manage them. The allergies are usually classified based on the pathway that they’re involved in.  Here are a few examples: 

  • IgE-Mediated Allergy – If you have a IgE-mediated allergy, you may have symptoms such as hives, rash, swelling, anaphylactic reactions.
  • Non-IgE Mediated Allergy – If you have a Non-IgE mediated allergy, you may have symptoms such as vomiting and diarrhea.
  • Eosinophilic Esophagitis (EoE)– An allergy-mediated disorder that leads to the inflammation of the esophagus which could cause you feeling like food is stuck when you eat.
  • Food Protein-Induced Enterocolitis Syndrome (FPIES) – An inflammation involving both the small intestine and the large intestine (colon). Typical symptoms include severe vomiting that may be accompanied with diarrhea within 2-3 hours of eating the food.
  • Allergic Proctocolitis – This typically affects young babies and could present as blood and mucus in the stool. 


Food intolerance does not involve your immune system and it is not life-threatening and it oftentimes involves your digestive system.  Typical symptoms may include bloating, cramping, diarrhea, and excessive gas.  Some examples of a food intolerance could be:

  • lactose intolerance – your body isn’t able to break down lactose completely
  • Fructan intolerance – your body is more sensitive to the break down fructan in your gut.  Fructan is a type of carbohydrate found in onion, garlic, some fruits, veggies and grain products, leading to IBS symptoms such as bloating, diarrhea, stomach pain
  • Non-celiac gluten sensitivity (NCGS) – your symptoms resolve on a gluten-free or gluten-reduced diet despite not having celiac disease.  You may have IBS-like symptoms.

Where to Get Food Allergy Tests?

If you’re wondering if you have a food allergy, it is important to note that a positive skin prick test nor a positive IgE blood test alone mean that you have an allergy.  Your personal history and symptoms are probably the most important tools in helping your doctor diagnose a food allergy.  Unfortunately, there are no valid food allergy tests for most of the non-IgE allergies – the diagnoses of these allergies often rely on your personal history, the presenting symptoms and/or an elimination trial.  EoE is diagnosed with an endoscopy and biospy.


There are a couple food allergy tests typically done through an allergist’s office to confirm a IgE-mediated allergy:  

  • Skin prick test – the allergist scratches the skin with a potential allergen and see if a reaction develops
  • IgE antibody blood test – the doctor or allergist test for the IgE levels of antibodies to a specific food protein and it can also be used to monitor over time to see when someone may be outgrowing an allergy
  • Oral food challenge is the gold standard – oral food challenges are often only done in the allergist’s office where they can treat the anaphylaxis reaction appropriately if this occurs.  The oral food challenge can be done to confirm a potential allergy and/or to see if you are outgrowing an allergy


And then in the market you will find all kinds of unvalidated food allergy testing, these testing should not be used in the diagnosis of food allergy or intolerance:

  • IgG food panel testing – one of the most common tests we see – the test checks for IgG antibodies in your blood against food proteins.  People who go for these testing often come up with a list of foods to avoid, many of which they are eating regularly in their current diet. The Canadian Society of Allergy and Clinical Immunology advised that IgG antibodies DO NOT indicate any food allergy.  In fact, allergist may use IgG antibodies to monitor tolerance for food reintroduction.  
  • Hair analysis – taking a sample of your hair to determine the food allergen.
  • Vega testing – using electric current when you’re holding the food allergen.
  • Apply kinesiology testing – testing your muscle strength to find if your muscles weaken when your body is exposed to certain food allergen.
  • Cytotoxic test – a sample of your white blood cell is evaluated under the microscope and see how it reacts with the food allergen.

Which Food Allergies are Most Common?

This is the list of priority food allergens in Canada and they account for about 90% of allergic reactions – wheat and triticale, eggs, milk, peanuts, tree nuts, crustaceans and molluscs, fish, sesame seeds, soy, mustard and sulphites.  Sulphites are not a “true food allergy”, but they do cause food allergy symptoms in people who are sensitive to them, so that’s why they’re included in this list.

Foods are labeled under their common names under the enhanced labeling law in Canada, and so it makes it easy for people to locate and avoid certain food allergen and find safe options for them.

Food allergen common names

How to Manage Your Food Allergy with Confidence

1. Strict avoidance is the best way to prevent a reaction

Always read the labels, every time as products can change frequently! Food Allergy Canada recommend triple checking your labels:

  • Once at the store before buying it
  • Once when you get home and put it away
  • Again before you serve or eat the product


2. Don’t be afraid to ask questions and/or educate

Especially when you’re eating out, ordering food or not sure about a product – asking the right questions can help you feel confident as well as an opportunity to educate others on food allergies.


3. Always carry your emergency medications (ie. Epinephrine) with you and know how to use it

Epinephrine is the only drug that can reverse symptoms of anaphylaxis and is considered life-saving medication and should be given at the start of a known or suspected anaphylactic reaction.


4. Build a Food Allergy Care Team

This might include your family members, close friends, physician, allergist, and a registered dietitian specializing in food allergies. Your care team can provide valuable education, support and help you develop a personalized plan for your allergy management. Each allergic individual case can be very different, this is why it is SO important to have a personalized plan in place in order to effectively to prevent and manage your food allergies.  


Become empowered with a good support system and knowledge about your food allergies! As you learn more, managing allergies will become part of your daily life. You will begin to feel more in control and live confidently with food allergies.


  • No comments yet.
  • Add a comment

    Elevate Your Health Journey with Expert Insights!

    • 🥗 Get personalized nutrition tips straight to your inbox.
    • 📚 Stay updated on the latest research in diet and health.
    • 🏋️‍♀️ Unlock exclusive content on sports nutrition, gut health, and more.
    • 🍎 Receive delicious and healthy recipes curated by our certified dietitians.
    • 📅 Be the first to know about our upcoming webinars, workshops, and special promotions.
    Reach out.