Food Allergy Testing

Dr. Sonya Nobbe, ND

Some of you may have viewed a CBC television report discussing food allergy testing, including IgG food intolerance testing that many NDs and other licensed health professionals use to gain insight into the body’s immune system responses. This piece may have generated more questions than answers, and we’d like to offer our patients some clarification.

Though we agree with most statements made by the medical professionals interviewed by CBC television and radio reporters, it’s important to understand exactly what these professionals were carefully acknowledging, as the language used can be a bit tricky. Following are some of the concerns identified in the broadcast, and our clarifications:

1. “IgG food intolerance testing” is not “food allergy testing”.

The immune system contains many immune pathways and may generate an inflammatory reaction against a food along any one of these pathways. Technically speaking, in mainstream medicine, the word “allergy” is reserved specifically for the type of pathway response called IgE, in which the body responds usually with a skin reaction like hives, or lung reaction like breathing difficulty (anaphylaxsis) when exposed to the irritant. Consequently, testing for immune reactions along another immune pathway such as IgG, is not the same as testing for “allergies”. It does however measure inflammation generated in a body against a specific food and the word “intolerance” may be used instead. The words “allergy” and “intolerance” are often used in healthcare interchangeably, though this is technically incorrect. (Interestingly, the definition of the medical word “allergy” is still regularly debated among professional societies.)

2. The science of IgG testing is not well understood.

Food reactions in general are poorly understood by the mainstream medical community. This is true of both IgG and IgE food reactions. Though we understand that we’re measuring inflammation associated with the body’s reaction against a food, the consequences of this in a body are still debatable. What we do know is that a huge body of medical research links chronic inflammation with the development and progression of chronic illness like heart disease and diabetes. It also undoubtedly links ‘poor’ diets with the development of chronic disease, and ‘healthy’ diets with reversal of chronic disease in some people. Food, inflammation, and chronic illness are undeniably connected. As a health practitioner who regularly uses IgG food testing to gain some insight into the body’s metabolism and immune function, I have observed countless times a definite cause-and-effect relationship between the foods that show up on IgG testing and manifestation of chronic symptoms, including asthma, digestive upset, neurological problems, and severe muscle pain.

3. Patients should not go on restrictive diets according to IgG food test results.

When interpreting IgG food testing results, it’s most important to retain a whole-body perspective, or “functional medicine” perspective, in which we view the body as an integrated unit. The utility of the test is in how it points to system imbalances that can be treated, rather than toward problematic foods. The problem isn’t the food – it’s in the body’s response to the food, and the IgG testing helps us to understand where this problem is occurring. A proper interpretation requires a thorough analysis of your medical history so that these connections can be made. Given that NO test results are as black and white as medicine would like them to be, ALL medical testing should be interpreted with a patient’s full medical history in mind. Consequently, we’d have to agree that simply removing the offending foods identified in the test results is not always an effective solution for a person’s health concerns.

Food allergy and intolerance testing is a complicated topic, and many of the answers are specific to an individual and their health concerns. If you have any questions about testing, please consult your Naturopathic Doctor.

The Ontario Association of Naturopathic Doctors has posted a press release in response to this topic, here.