Food Intolerance Testing
I have some magic beans for you…if you aren’t intolerant
Much like adrenal fatigue, Food Intolerance Testing (FIT) has become a new pseudoscience method for “fitness professionals” and pharmacies to sell laboratory tests, dietary services, and supplements under the guise of treating what is, in most cases, a non-existent condition. Best case scenario is that professionals who support this type of testing are simply uneducated on the topic, worst case is that they may be blatantly taking advantage of patients for money.
Food Intolerance Testing comes in many forms: Hemocode, YorkTest, ALCAT, Foodscan, vega testing, K-Test, hair testing, provocation-neutralization, cytotoxic tests, muscle response testing (applied kinesiology), electrodermal testing, the “reaginic” pulse test, and chemical analysis of body tissues. The most common FIT modalities use IgG (sometimes referred to as non-IgE) protocols to identify intolerances. Non-IgE reactions are a delayed immune reaction, Celiac disease being an example. These types of responses are different than an immediate immune response (IgE located on Mast cells) that is commonly associated with dangerous allergic reactions such as anaphylaxis, immediate flushing, throat swelling, vomiting etc.
The American Academy of Allergy Asthma and Immunology differentiates intolerance from allergy by suggesting that intolerances generally involve the gastro-intestinal system, whereas immediate allergies involve the immune system. This is often confusing, and frankly vague, since FIT is based on identifying an immune system antibody, IgG. In reality, IgG signifies exposure to foods and may actually be a marker of food tolerance rather than intolerance.4,5,6,7,17
Food intolerance testing is problematic for many reasons. FIT has never been proven to be accurate, nor does the basis of the testing itself follow likely plausible mechanisms for identifying a sensitivity.1,8,9,10 Even more concerning, it has the potential to promote eating disorders through food avoidance. This unwarranted fear mongering is the real danger of intolerance testing. It can exacerbate already poor relationships with food, which can ultimately lead to lowered health status.
According to Dr. Robert Hamilton from Johns Hopkins University “There is no firm, peer reviewed data that verifies that IgG antibody is diagnostically useful, this type of food sensitivity/intolerance test is essentially a bogus test.” The most succinct explanation of what is happening with FIT comes from Huston & Cox 2014 when they say: “A positive IgG [in some cases labeled as non-IgE] test result for a food allergen just means that an individual has been exposed – in other words, has eaten the food before.” Dr. Hamilton expands on this with: “it doesn’t mean that you are sensitive or intolerant to those foods. And it certainly doesn’t mean you should avoid exposure to them, or avoid eating them. This type of test is basically totally inappropriate. And how it can get on the market, and be sold, with these claims, is very disturbing.”3
Funny enough, this can be anecdotally evaluated in day-to-day practice. Taking a food intolerance test, eliminating those foods from your diet, then weeks to months later taking another test from a separate company has been shown to yield completely different intolerance results. This is likely due to the new host of food exposures and their subsequent IgG antibodies.
Food intolerance tests are considered “laboratory-developed tests”, and therefore they are not legally required to be evaluated by the FDA.2 Because of the dubious science associated with them, the American Academy of Allergy Asthma and Immunology (AAAAI), the Australasian Society of Clinical Immunology and Allergy, the Allergy Society of South Africa Position Statement: ALCAT and IgG Allergy & Intolerance Tests, the National Institute of Allergy and Infectious Diseases Guidelines for the Diagnosis and Management of Food Allergy in the United States, the European Academy, the Canadian Society of Allergy and Clinical Immunology, and prominent immunologists all take the position arguing that individuals should not use FIT to identify food intolerances.11,12,13,14,15,18,19 They, in fact, do not support food sensitivity/intolerance testings of any kind (not only limited to IgG).
The American Academy of Allergy Asthma and Immunology states in Allergy diagnostic testing: an updated practice parameter: “IgG and IgG subclass antibody tests for food allergy do not have clinical relevance, are not validated, lack sufficient quality control, and should not be performed.” This is not to say that food intolerances do not exist. The currently recommended identification methods include eliminating and subsequently reintroducing suspected foods as well as blind placebo exposures to identify food intolerances. These require time and adherence to perform accurately.
Lastly, mental anxiety regarding the foods themselves can also act as a self-fulfilling infliction. Individuals that are concerned they have a sensitivity to a specific food may be producing a nocebo reaction (the phenomenon that believing in the negative effects of a stimulus will actually make you experience those negative effects). Dr. Emeran Mayer, a gastroenterologist and the director of the Oppenheimer Center for Neurobiology of Stress Ingestive Behavior and Obesity Program at the David Geffen School of Medicine at UCLA, believes that this mental/emotional stress can cause a host of changes in the GI tract: impaired motility, digestion disturbances, mucus secretion alteration, and ultimately gut microbiome imbalances as a result.3 To the patient, this can falsely justify the preconceived notion that they are intolerant to a suspected food.
Due to the lack of clinical backing for over-the-counter food sensitivity/intolerance tests, it is best to save your money. If a true food allergy is suspected, “For any patient who does have a history of allergy symptoms, the appropriate allergy testing is for allergen-specific IgE.” The AAAAI also points out that allergen-specific IgE testing should be limited to allergens suggested by the clinical history of the patient. IgE tests must be done under careful, clinical consideration. The AAAAI does not recommend an indiscriminate battery of allergy testing for patients.16