Clarifying Myths on Food Intolerance Testing

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Clarifying Myths on Food Intolerance Testing

Written by Dr. Sandra Miranda, ND

First of all, we need to recognize the difference between a food allergy and a food intolerance or sensitivity.  A food allergy (IgE response) is an immediate reaction to a food that can cause your throat to swell up, hives, etc and for which you need an epi-pen.  An example of a food allergy is peanuts in children.

A food intolerance (IgG response) is a delayed reaction which can occur up to 3 days after ingesting a food.  This is the reason why testing is so helpful because it is close to impossible to figure out food intolerances by just doing diet diaries.  These IgG antibodies attach themselves to the food and form a complex, which if not cleared by the immune system, then can cause inflammation in different parts of your body such as skin, muscle, joints, vessels, nervous system etc.  Therefore, common symptoms of food intolerances are: skin rashes / eczema, aches and pains, migraines or headaches, fatigue, bloating, etc.

There are some misconceptions about food intolerances and the testing, that I would like to shine a light on:

Myth #1 – There is no value in doing a Food Intolerance Test.  

This is not true! There is something called a “growing body of evidence” to support the clinical benefits of eliminating IgG reactive foods from your diet.  I am including some studies at the bottom of this article that show how food sensitivities have been implicated in migraines, irritable bowel problems and inflammation and obesity. Continued consumption of reactive foods may contribute to increased inflammation and weight gain.


Myth #2 – An IgG response is only an indication of exposure and not intolerance.

Again this is not entirely true!  I do agree that the more you are exposed to a food the more chances you have of the IgG levels to that specific food being high but that is because you have more chances of becoming intolerant to that specific food.  The reason why I know this myth is wrong because I may have a patient who has a protein shake every morning with cow’s milk, whey protein powder, a banana and ground flax seeds and may become intolerant to the cow’s milk and to whey but not to bananas or ground flax seeds.  She is exposed to bananas and ground flax seeds daily yet the IgG levels to those 2 foods have not risen.


Myth #3 – Eliminating food intolerances can potentially be hazardous to your health.   

Again, this is only true if you are not being followed by a qualified, licensed Naturopathic Doctor or practitioner trained in nutrition and in interpreting food intolerance tests.  Removing a whole bunch of foods from your diet and not replacing them with the many, many nutritious options that are available nowadays is WRONG! This is not something any qualified and licensed Naturopathic Doctor will ever recommend.  We thankfully live in a time when there are many alternatives to dairy, protein, gluten grains, spices, etc. Just because you have food intolerances and need to remove some from your current diet, does not mean you need to starve yourself and become malnourished.  If you feel that you are not eating enough then you need to do a 3 day diet diary and make a consultation with your Naturopathic Doctor to fix the problem.  In addition, there are patients who have many food intolerances, in those cases the answer is not to remove all the foods but to FIX THE GUT!  If you are having many food intolerances then right away the treatment should be focused on how to fix your digestive walls, flora, ability to digest your foods etc. Patients with an increased gut permeability will have more food intolerances.


Myth #4 – The results are invalid because I have no adverse reactions to the foods that came back positive.

It is important to understand how to interpret the results.  First of all, it is important to keep in mind that the reactions can be delayed – up to 3 days later.   Food intolerances are very different to a food allergy which are immediate reactions. In addition, it is important to note that we have immune system cells called macrophages that are constantly trying to clear up these IgG- antigen complexes.  So if you are only eating 1 or 2 foods that you are intolerant to, you may be lucky enough to have your immune system clear up the mess. However, if your immune system is low or if you have just consumed a combination of many of your food intolerances then your macrophages will have a limited ability to clean up that mess, and then you can have a symptom from it.

Many health organizations are warning people about the misinterpretations of IgG tests and I agree!  I think there is a time and place when a food intolerance test can be valid but you must be working with a qualified and licensed Naturopathic Doctor to know how to interpret the test results.  A food intolerance test is not intended to be a single tool to be used alone in order to treat somebody’s health concern. It is meant to be used as a possible part of a comprehensive treatment plan that will address the root cause of your health problem.


For those of you who are more science oriented.  Here are actual studies that you can read.

Studies on how food intolerances can affect migraines:


Studies on how food intolerances can affect irritable bowel (IBS and IBD):


Study on how intolerances are related to inflammation and obesity:


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