How Do I Interpret my IgG Test?

Your immune system makes five different types of antibodies denoted by different letters: G, E, A, M and D. The G type of antibody is the most common (80%) and is part of your gut's defense team.

Having IgG antibodies for specific foods in your blood is natural and common. However, should the IgG antibody levels climb higher than normal, the body's ability to safely remove them from circulation is compromised with risk of symptoms developing and chronic inflammation. There is a growing body of evidence suggesting IgG food sensitivities do play a role in the development of a variety of diseases. f IgG antibodies, or Type III hypersensitivities can be measured via a simple blood test.

Most laboratories compare your blood sample vs expected antibody levels or population data to identify when a hypersensitivity immune reaction has developed. Most of the foods we eat generate a "normal" immune response of less than 30 U/ml IgG antibodies per food protein. Allergists consider this an expected and natural outcome because food is considered "foreign" by your immune system. Consequently, an IgG antibody score higher than 30 U/mL is not expected and the higher the score, the more inflammation and symptoms can result. Published research shows the benefits of removing these IgG-reactive foods from your diet for a growing number of health conditions. s Using population data to determine normal ranges for IgG food reactivities by some laboratories can be very misleading if the population analyzed has abnormally high reactivity to the foods tested.

For eg, approximately 40% of Canadians have IgG sensitivities to dairy products (1). An Italian study (2) also measured an elevated IgG immune response to dairy and egg proteins in 6879 Italians. So this may explain why your score of 112 for cow's milk or casein (dairy protein) is considered "borderline" by some labs vs "elevated". Using population bell-curves to assess the appropriateness of your own body's health is suitable for most medical blood tests. However, it may not be ideal for assessing IgG Type III hypersensitivities which are more likely determined by your own dietary preferences and maybe even your own family gene pool. The more you eat a specific food the more likely IgG antibody levels for that food will rise. So when you review your test results remember that IgG antibody levels are expected to be below 30 U/mL for each food. Higher scores are likely indicative of an abnormal response and need to be addressed with the help of your healthcare practitioner. 

References: 1. Verbal communication (2016, RMA Lab) 2. N Volpi and F Maccari J Immunoassay Immunochem 2009;30(1):51-69.