Why You Should Be Wary of the Food IgG Test
Leading allergy organizations around the world – including the American Academy of Allergy, Asthma, and Immunology, the European Academy of Allergy and Clinical Immunology, and the Canadian Society of Allergy and Clinical Immunology - have recommended that IgG tests not be used in the diagnosis of food allergies, intolerances, or sensitivities. Nonetheless, companies continue to push their food IgG tests on unsuspecting patients. At best, these tests are a waste of time and money. At worst, they result in misinformed patients who lack an understanding of their body’s reactions to certain foods and how best to manage potentially problematic reactions.
What is wrong with using the IgG test to identify adverse reactions to foods? Unfortunately, there is no scientific evidence that strongly suggests that IgG is predictive of one’s reaction to foods. According to expert allergists and immunologists, high IgG levels likely reflect a perfectly normal immune response to food, and a particularly high IgG level may indicate that someone has a good tolerance for the food in question. Nonetheless, someone administering a food IgG test who found high levels of IgG in response to the consumption of a certain food would tell the patient that the food had caused an adverse reaction.
Another significant problem with clinics using the IgG test to help patients make decisions about their diets is that these clinics often use the concepts of food allergies and food sensitivities interchangeably, though food allergies and food sensitivities represent vastly different bodily responses to food. A food allergy poses a potentially life-threatening situation wherein the immune system reacts to what could potentially be a very small portion of the food allergen. A food sensitivity, on the other hand, tends to refer to a reaction in the gastrointestinal (GI) system that is dose dependent, meaning that the more of the substance one consumes, the more affected they are.
In practical terms, when someone has a food allergy, they tend to have to avoid that food altogether. With food sensitivities, there is often no reason to avoid the food, but the patient may want to reduce the amount of that food they consume so that it does not cause them discomfort. Whereas a food allergy may lead to tongue swelling and difficulty breathing, a food sensitivity is more likely to cause bloating, stomach pain, and diarrhea.
Given that food allergies are much more serious than food sensitivities and should be dealt with in a more urgent manner, people who are concerned that they may adversely react to certain foods but are unsure if they have an allergy or sensitivity should consult a licensed allergist or immunologist so that they can be properly screened for allergies. These physicians can help to navigate symptoms and food reactions and determine the best course of action to ensure patients’ safety and comfort.