We live in a time where food allergies and intolerances are more prevalent than ever before. In my practice I see a ton of allergies and intolerances.

Why is this?  I have a few theories.

  1. Increased antibiotic exposure (see my recent post on Leaky Gut for more)
  2. We live in an over-sanitized environment
  3. Paranoia & information overload 

My goal is to eliminate reason # 3 and give you the facts.


First, let’s go over Food Intolerances vs Food Allergies. Food Intolerance is not immune-based, but rather, is an irritation to a given food that can present themselves in a wide variety of ways. Symptoms of a food intolerance can range from hives to congestion to stomach issues. These types of reactions may take anywhere from hours to days to present themselves and can begin at any age.

In contract, a Food Allergy involves an immune response to food. With a food allergy, individuals will make IgE antibodies to the proteins in those foods they are allergic to. As a result of these reactions, various chemicals are made, including histamine. Histamine causes many of the allergy symptoms and this is why antihistamines can be used to treat some allergic reactions.

Symptoms of food allergies involve rashes, breathing issues, vomiting and even anaphylactic shock that can lead to death if immediate intervention is not given. While intolerances can begin at any age, food allergies most often have an onset in the very early ages, more specifically, in infants and toddlers.

Types of Allergies

Not all food allergies are IgE mediated. I will dive into additional types of allergies during Part 2!  During Part 2 we will cover:

  • Oral Allergy Syndrome
  • Delayed-Onset Food Allergies
  • Exercise-Induced Anaphylaxis (note – I have this)
  • and more!

Allergy Testing

There are a number of different tests out there and it can be confusing to know which one to go for. It is important to note that none of these tests are without errors!

  • Skin prick tests provide results in about 20 minutes. A liquid containing a tiny amount of the food allergen is placed on the skin of your arm or back. Your skin is pricked with a small, sterile probe, allowing the liquid to seep under the skin. The test is considered positive if a wheal (resembling the bump from a mosquito bite) develops at the site where the suspected allergen was placed. As a control, you’ll also get a skin prick with a liquid that doesn’t contain the allergen; this should not provoke a reaction, allowing comparison between the two test sites.
  • Blood tests, which are a bit less exact than skin tests, measure the amount of IgE antibody to the specific food(s) being tested.  Your allergist will use the results of these tests in making a diagnosis. However, these tests are not without errors – a positive result doesn’t mean that there is necessarily an allergy, and it is possible to receive a false positive. It is best to go to your allergist with potential trigger foods, that may have caused symptoms already. For me, I had a reaction to a peanut-containing birthday cake when I was 4 years old, a received a skin prick test from the allergist to confirm this reaction.
  • In some cases, an allergist may wish to conduct an oral food challenge, which is considered the most accurate way to make a food allergy diagnosis. During an oral food challenge, which is conducted under strict medical supervision, the patient is fed tiny amounts of the suspected trigger food in increasing doses over a period of time, followed by a few hours of observation to see if a reaction occurs. This test is helpful when the patient history is unclear or if the skin or blood tests are inconclusive. It also can be used to determine if an allergy has been outgrown.


Intolerance Testing

It is important to note that there are no true diagnostic tests for intolerances. Instead, it is often a combination of the patient’s history, tests and symptoms.

What about IgG testing?
The literature currently suggests that the presence of specific IgG to food is a marker of exposure and tolerance to food, as seen in those participating in oral immunotherapy studies. Hence, positive test results for food-specific IgG are to be expected in normal, healthy adults and children. In other words, a positive IgG result happens in response to foods you are already eating, not necessarily as an intolerance response. Having a positive IgG response to certain foods does not mean that your body is reacting negatively against this food.

Buyer Beware. These tests tend to suggest long lists of foods that could be avoided unnecessarily. This can lead to the exclusion of multiple foods from the diet. Whilst this might be unhealthy for an adult, it can be positively harmful in a child or an adult with complex medical health needs. An extremely restricted diet can lead to severe nutritional deficiencies and eventually to malnutrition.

What To Do

  1. If you suspect a food allergy:Visit an allergist/immunologist, which is physician specially trained to manage and treat allergies and asthma.
  2. If you suspect a food intolerance:Testing for non-allergic (non-IgE) food sensitivity reactions is meant to be a tool for identifying triggers and designing an appropriate elimination diet protocol, which will re-introduce foods over time as tolerated/indicated – as is the goal of FODMAP protocol – and often best done under expert guidance as well. The food should be excluded from the diet completely for 2-6 weeks, to see if symptoms improve. It is never meant to be list handed over to patients as a type of avoidance diet itemizing their “no-no” foods!! 

    A patient’s degree of success can be highly dependent upon the degree of guidance they receive. Especially considering elimination diets often involve reactions that are not immediate—as well as being highly dose dependent, plus may even incorporate food-chemicals. It is important to work with a Registered Dietitian who will guide you in developing an elimination diet protocol, while ensuring your diet remains well-balanced.


Research by Chelsea Cross, BASc


1 comment

  1. I am glad that your article mentions the importance of visiting an allergist if you suspect any issues. My daughter does not feel well when she consumes shellfish. I’ll contact an allergy doctor in the future.

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