Doctors Warn Against the IgG Food Sensitivity Test


There is a lot of confusion and misinformation about food sensitivities in today’s culture of what-to-eat and what-not-to-eat.  Whether you suffer from migraines, infertility, weight or digestive issues, you may look to your diet for answers.  The Canadian Society of Allergy and Clinical Immunology is warning against the ELISA IgG food sensitivity blood test that is promoted by many alternative practitioners as a cure all.  The scientific community has proven that IgG antibodies are unrelated to food intolerance or allergy symptoms.  In fact, studies have shown that IgG antibodies indicate quite the opposite: that a person has been exposed to a food. 

FACT #1: IgG Antibodies Mean Your Body is Used to a Food

An excellent study published in the Allergy journal, demonstrated this many years ago by showing that people who worked in a bakery had high IgG levels for wheat and do not actually suffer from wheat sensitivity.  The IgG test could not identify the individuals who actually suffered from wheat sensitivity.  Interestingly, in this study the researchers also noticed that half the study participants also had high IgG antibodies to animals, but none of them were allergic to animals.  The researchers explained that if you own a pet, you will likely have high IgG antibodies to animals, because you are used to your pet, not because you are allergic to it. 

FACT#2: Sometimes the IgG Tests Guess it Right, by Chance

One  study that is often quoted by supporters of the IgG test, gave an IgG food elimination diet to patients with Irritable Bowel Syndrome, which resulted in up to 26% improvement in symptoms.  However, this study was flawed because they eliminated dairy and wheat in the IgG test diet, which are well known triggers for people suffering from IBS.  The IgG test identified dairy and wheat because they are common foods that everyone has been exposed to.  In this way, when the IgG test identifies these two known IBS trigger foods, it can identify food sensitivities correctly by chance.  Keep in mind, that the low FODMAP diet, the recommended diet for people with IBS, effectively reduces symptoms in 75% of people with IBS.

FACT #3:  IgG Food Elimination Diets are Unnecessary and Unhealthy

Most IgG elimination diets would have you remove key staples from your diet like wheat, dairy, egg and certain fruits and vegetables.   This makes it difficult to get enough food and nutrients and difficult to follow such a restrictive diet.   This is a particular concern for growing children.

FACT #4:  There is Only One Way to Identify Food Sensitivities

Doctors, allergists and immunologists do recognize that food sensitivities do exist; however, they explain that there is no medical test that can identify food sensitivities.   Allergists remind us that the only way to identify and diagnose a food sensitivity is through the long and difficult process of a food elimination and challenge diet.  In a nutshell, this involves cutting out all suspected foods for several weeks until symptoms improve, followed by a phase of reintroducing each new food one-at-a-time to look for symptoms to come back.  Only in this way, under the guidance of an experienced health professional can a person correctly identify their food sensitivities.  Perhaps it is this daunting task that has opened the market up to a quick fix. 

It can be extremely frustrating to find answers to complex food sensitivities.   A thorough food and symptom journal and careful elimination of suspected foods under the guidance of an experienced registered dietitian, can be the beginning of the journey to feeling better.

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