Clients often ask me, “how do you know if it’s a food allergy or a food sensitivity or a food intolerance?”

First,  it’s important to define allergy. An allergic reaction describes what happens when the immune system inappropriately identifies, labels and attacks a substance that it finds dangerous to the body. This substance is usually something that does not cause any such reaction in the majority of individuals. More broadly, the reaction is called a hypersensitivity reaction.

The time is takepeanut butter sandwichs for these symptoms to appear along with the degree of severity of the symptoms mirror what type of of hypersensitivity is occurring. For example, a classic allergy describes an immunological response to a substance within 4 hours of exposureAnaphylaxis is the most dangerous type of classic allergic reaction, but most classic allergies are not actually this severe.  Allergists tend to be very confident diagnosing classic allergies because they can be reproduced while at the doctor’s office using the skin prick test. Here, food particles are applied to the skin and the skin is scratched with a needle.  If the client experiences a skin reaction to the substance within 15 minutes they are said to be allergic to that substance.

Why We Can’t Depend on the Scratch Test

The skin prick test cannot be viewed as the definitive test for food sensitivity because it can only identify IgE antibody-mediated reactions that affect the skin. However, classic allergies to pollens, animal dander and other airborne substances can be accurately diagnosed using this test.  But it is important to recognize that most food reactions are actually IgG-mediated and occur anywhere inside or on the body, more than 4 hours after exposure.  This is why if your results of the skin prick test are all negative for foods yet you experience symptoms more than 4 hours after consumption of the food, you may still have an unidentified food sensitivity.

In contrast,  food sensitivity / food intolerance are terms used interchangeably to describe an immunological reaction that occurs between 4 hours and 3 days from the time of exposure. Medical doctors may deny that food sensitivity or intolerance is a form of allergy because there are so many variables interacting with the client after the 4 hour period that is hard to link to a substance.  For instance, the client may eat a combination of foods, change geographic locations (from office to home, for example), and experience various other stressors and exposures such as to viruses or bacteria within the 3 days that it can take for a delayed hypersensitivity reaction to an ingested food to occur. This makes it hard to trace which food one reacted to.

A Useful But Costly Test

Fortunately, there is an accurate blood test for hypersensitivity identification available through your physician or Naturopathic doctor.  This blood test for food intolerance/sensitivity measures IgG antibodies which are involved in delayed reactions (4 hours+). It is accurate as long as one has eaten the food within the past month or so. However, this test costs about $350.  Note that this one is not covered by OHIP (Ontario Health Insurance Plan).

So, while both tests have good accuracy when applied correctly, they cannot be used interchangeably as they provide different information.

Is Self-Assessment Accurate?

CB043875Undeniably, it can be difficult to self-assess and correctly determine one’s food sensitivities.  A holistic nutritionist can provide instruction on how to most accurately self-assess without compromising nutritional status. This method will involve removing all ingredients of suspect foods for a given length of time, and then re-introducing them in a systematic way.  When done properly, without ‘cheating’, this is an inexpensive way to go. In my practice, I have found this method very helpful for numerous clients, who often will say, “after doing this procedure, I can see that ‘x” is what’s aggravating my symptoms.”   It will be obvious after un-masking the allergy—that is, taking a break from the suspect food for a specified period of time and then re-introducing it back into the diet—when the food is involved in deterioration of well-being.

What foods do you react to?

Please note:  holistic nutritionists cannot diagnose allergies or sensitivities; they provide instruction on how to help clients isolate which foods may be involved in their health complaints.


By Andrea

2 thoughts on “The Difference Between Food Allergy, Sensitivity and Intolerance”
  1. My daughter and I had the food intolerance panel run last year and it was very helpful for identifying things that were not caught during a typical allergy elimination diet. For example she reacts very badly to rice and I react very badly to celery, both would typically be allowed on an elimination diet. Definitely worth the money in our case, although it was a big investment. For myself I don’t mind removing foods and adding them back to judge how i feel, but for kids it’s hard for them to articulate how they’re feeling, or to tell if it’s food or another factor that is influencing say behaviour or sleep.

    Elimination diets are great starting point for people, but the food intolerance testing is worth the money if you still have symptoms after or (IMO) for kids.

    1. Hi Maranda. Thanks for sharing those uncommon sensitivities. It shows anyone can react to anything. I agree that with children it’s harder to know what they are reacting to based on the subjective “I feel”. Also, for adults and children alike we are counting on them following the elimination diet 100% with no cheating, the latter which will make the experiment invalid since we need 10 days to unmask the sensitivity. I continue to recommend the IgG panel for identifying uncommon sensitivities after an unproductive MED diet.

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