Food Allergies 101

Ever noticed you’d breakout or get a stomach ache after digesting a certain food? Have you never noticed such a correlation as your reactions manifested themselves up to 4 days later? You might have a food allergy, intolerance, or sensitivity – and not know it!

About 20-30% of the population reports having a food allergy today (Mansoor, D.K. & Sharma, H.P., 2011, p. 315). The 8 most common allergens are: wheat, soy, milk, egg, treenuts, peanuts, seafood, shellfish. In Canada, sesame, mustard, and sulphites are recognized as well, for a total of 11 common food (IgE) allergies.

IgE? I’ve heard about IgG and IgA, too… what does this all mean?

IgE: These are usually immediate allergic reactions (typically occurring within the hour of ingestion, but not always); may be life threatening. These are the ones people associate with, say, peanut allergies.

IgG: These reactions, associated with food intolerances, may be delayed for 4-7 days, not usually life threatening.

“The half-life of an IgG antibody is between 23 and 96 days, which makes it challenging to identify reactive foods solely through elimination diets or observation. This also means it can take more than a year for food-specific IgG antibodies to disappear after elimination from diet” (Trevorrow, M. & Marsden, T, 2012, p. 38).

Read page 3 of this PDF to understand what some common food reactions may look like.

IgA: These antibodies are produced in normal mucosal tissue, particularly the gut, and are made by the immune system to fight bacteria, viruses, and toxins. The blood level of immunoglobulin A is measured to diagnosed Celiac’s disease.

You can diagnose allergies via blood tests, skin prick tests, and well, exposure. (Note that none of these methods may be 100% accurate.)

Note that you can develop new allergies at any time in your life. Food allergies are often associated with bowel issues, heavy metal overdose, parasites, and/or Candida overgrowth (Martin & Rona, 2000, p. 481).

How do allergies develop? Leo & Jonathan Galland simplify the process in their book The Allergy Solution (2016) on page 41:

Exposure to a trigger (an allergen/antigen) –> amplification of the signal by the immune system –> effects

You may think, “Who cares if you’re intolerant of kale if your reaction doesn’t result in anaphlaxis? Let them eat kale! …but repeated exposure to “sensitivities” can still be problematic.

 Non-IgE-mediated food reactions can still cause many symptoms. Identifying your food intolerances and avoiding them may alleviate your symptoms, help you lower your body’s inflammation & calm the immune system down so it can recover.

Personally, I’ve found avoiding my intolerances has resulted in experiencing less flare-up symptoms now, especially GI tract-related ones. Plus, it’s supposed to help my body be less stressed instead of having to combat food proteins it doesn’t like everyday, so to me, identifying my food intolerances was definitely worth it.

Catcher of the Rye Labels & Catch 22
“Okay, you can’t have rye, but you can eat rice… so why not just eat your safe foods all the time?” you ask. Well, everything in moderation! Repeated consumption of safe foods can lead to the development of a new allergy against them.

Rotation Diets
That’s why many follow rotation diets, meaning they rotate foods by food groups every 4-7 days. In other words, many eat foods from one food family for 24h and then don’t touch them for another 96h. (That’s how long it takes for food to travel through the digestive system… in theory.)

Check out these links for more information:
Link 1, Link 2, Link 3

“OAS with Seasonal Allergies? Oh my!”

Now of course, some people only experience allergic reactions to food during certain times of the year, when seasonal allergen levels are high. This is called Oral Allergy Syndrome (OAS) – and I’m a “seasoned” OAS girl.

Typical symptoms of oral allergy syndrome include: itchy mouth, scratchy throat, or swelling of the lips, mouth, tongue, and throat. Itchy ears are sometimes reported too (ACAAI, 2014).

The ACAAI states that this is caused by “cross-reacting allergens found in both pollen and raw fruits, vegetables, or some tree nuts” (ACAAI, 2014). In other words, the immune system may mistaken the pollen and similar proteins in the food and set off an allergic reaction to it.

For example, if you are allergic to ragweed, chances are you might not be able to eat raw zucchini, squash, or melons during ragweed season (August – first frost).

Consult the Canadian Food Inspection Agency’s website here for a detailed list of common cross-reactivities between foods and pollen.

What’s the solution?
Eating these offending fruits and veggies in cooked form will usually solve this issue, as  the heating process distorts the proteins. However, this isn’t always the case for everyone, so sometimes it’s best to just avoid certain foods until the pollen levels decrease.

If you have any questions or want further clarifications, feel free to send me a message!


American College of Allergy, Asthma & Immunology (ACAAI). Oral Allergy Syndrome. ACAAI. Retrieved from

Galland, L. & Galland, J. (2016). The Allergy Solution. Carlsbad, California: Hay House Inc.

Mansoor, D. K. & Sharma, H. P. (2011). Clinical Presentations of Food Allergy. Pediatric Clinics of North America, 58(2): 315-326. Retrieved from

Martin, J.M. (2000). Complete Candida Yeast Guidebook (2nd ed.). New York, New York: Three Rivers Press.

Trevorrow, M. & Marsden, T.  (2012). Food Allergies and Sensitivities: Observing the Complete Picture. CAND Vital Link. 33-39. Retrieved from

Zarkadas M., Scott F.W., Salminen J., & Ham Pong A. (1999). Common Allergenic Foods and Their Labelling in Canada – A Review. Canadian Journal Allergy & Clinical Immunology. 4: 118-141.