Upset stomach, bloating, irregular bowels, aches, pains… sounding all too familiar? Wouldn’t it be wonderful if one test could offer all the answers on how to be free of these symptoms for good? That is exactly what Immunoglobulin G (or IgG) testing is being marketed to provide. With such enticing promises, it’s clear why so many people are turning to IgG food sensitivity testing for answers.
What is IgG testing?
The hypothesis behind IgG testing: an individual’s immune system reacts to usually harmless food proteins and produces IgG antibodies. These antibodies lead to inflammation in the body which in turn leads to various health concerns. Getting IgG testing done involves providing a single blood sample (which, depending on the test provider, is collected in a lab or through a home collection kit) that is analyzed for potential food sensitivities/intolerances.
The difference between allergies and intolerances
Before we take a closer look at IgG testing, it’s important to keep in mind the differences between food allergies and food intolerances. Responses to food intolerance usually involve unpleasant digestive symptoms (such as bloating, gas, loose bowls); and the onset of symptoms could be several hours–or even more than a day–after the food was eaten. Individuals with a food intolerance can often ingest small amounts of the food without experiencing symptoms. Think about those with lactose intolerance: they might be able to have a small splash of milk in their coffee without suffering symptoms, but they cannot tolerate a glass of milk.
Responses to food allergies involve the immune system (most typically) producing antibodies called Immunoglobulin E, or IgE for short. Symptoms usually occur anywhere from seconds or up to a couple of hours after exposure. These symptoms could include:
- respiratory symptoms (wheezing, difficulty breathing),
- skin reactions (redness, hives, swelling, itching),
- gut symptoms (vomiting, diarrhea),
- issues involving cardiovascular symptoms (rapid heart rate, low blood pressure).
Unlike an intolerance, a food allergy can cause a serious or even life-threatening reaction when an individual is exposed to even a microscopic amount of the offending food.
About IgG (Immunoglobulin G)
Immunoglobulin G is one of five classes of immunoglobulins (or antibodies) the body produces. It is the most abundant of the immunoglobulins and can be found in all the body’s fluids. The immune system signals the body to produce IgG when it is exposed to a foreign substance – from bacteria and viruses to foods. The purpose of food-specific IgG is not entirely understood as of yet, but it has been theorized that IgG/food complexes can lead to inflammation and disease; hence the boom of IgG testing in recent years. There are several companies in North America that offer IgG testing. You might also have seen an advertisement for it in your pharmacy at some point.
So is IgG testing the answer we’ve been waiting for?
Sadly, it does not seem to be the case. In fact, the scientific literature currently available suggests that IgG is a marker of tolerance and prior exposure as opposed to intolerance. IgG testing has been discredited by allergy and immunology societies around the world, including the Canadian Society of Allergy and Clinical Immunology (CSACI), as a diagnostic tool for food intolerances.
Results of IgG testing usually produce an extensive list of foods for individuals to avoid. This makes meal planning very challenging and puts individuals at risk for nutrient deficiencies. Another big concern with IgG testing is the lack of standardization between labs that offer this testing; individuals will get a different result from each different testing company. One will likely also get different results from submitting a sample from the same person to the same company on two different occasions.
Then why do some people feel better after getting this testing done?
There are a number of reasons why IgG food sensitivity testing has yielded great outcomes for some individuals. Someone might have eliminated a food that was causing symptoms, but chances are that person also eliminated several other foods that may not have been an issue at all. Based on test results, people typically must eliminate most processed foods from their diet. They are also usually meal planning, cooking at home more often, setting aside time for meals, and paying close attention to what they eat in general; these are all steps in creating a healthier diet overall. In short, people often feel better because their diet is healthier, not necessarily because they have eliminated certain foods.
What is the alternative?
Your Copeman team would love to help! There could be several factors contributing to your symptoms. Speak with your doctor to rule out/treat any medical causes. Next, your dietitian can assist in reviewing your diet. While working with your healthcare team, consider keeping a food, mood, and symptom diary; it can be a very helpful tool in identifying potential symptom triggers. A good old paper journal works just fine, but for those looking for a high-tech version, smartphone apps like Cara are very useful.
Not ready to speak to your dietitian? Take the first step by checking out this article on managing food sensitivities.