IgG food sensitivity testing is a blood test that I utilize in my naturopathic practice to help my patients personalize their diet while transforming their health and energy in the process. In this blog post I discuss the science behind food sensitivity testing, as well as the advantages and disadvantages of using IgG food sensitivity testing to personalize your nutritional approach.
This is the fourth article in my blog series all about food sensitivities, which has also included these other posts:
- 10 Signs that you may have Food Sensitivities or Intolerances
- What’s the Difference Between Food Allergies, Sensitivities & Intolerances?
- Top 10 Most Common Food Sensitivities and Intolerances
Food Sensitivity Testing — Is it Science-Based?
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What is IgG Food Sensitivity Testing?
IgG food sensitivity testing is a blood test that enables you to identify delayed immune reactions to foods that you may be eating as part of your everyday diet. Food sensitivities are different than food allergies, and food sensitivity testing assesses for the elevated levels of IgG antibodies that are associated with this specific type of immune response.
Is there Science that Explains IgG Food Sensitivities and Intestinal Hyperpermeability (a.k.a. “Leaky Gut Syndrome”)?
Food sensitivities are mediated by a delayed immune reaction to specific foods. Due to the timing and nature of the symptoms produced by food sensitivities, people may be consuming foods they are sensitive to on a day-to-day basis without realizing they are the cause of these concerns. This delayed immune reactivity can lead to chronic, body-wide symptoms including digestive upset, bloating, fatigue, eczema, acne, joint pain, and headaches.
The immune reaction itself is triggered when food proteins pass from your digestive system into your bloodstream without first having been 100% digested in your small intestine. It’s helpful to think of food proteins as a beaded necklace, with each bead representing a small sub-unit that’s called an amino acid. The job of your digestive system is to break the necklace down into individual beads (amino acids) in order for them to be absorbed into circulation and used as building blocks to create new cells, hormones and neurotransmitters. If the individual beads are absorbed one at a time, your immune system recognizes them as the protein-based building blocks that your body requires for survival.
In a well functioning digestive system, the majority of proteins will be absorbed as individual “beads”. However, if a string of multiple beads is absorbed all at once your immune system will flag that particular protein as something that it should further investigate. This can become a common occurrence if you experience intestinal hyperpermeability, which means that the barrier between your digestive contents and your bloodstream has become “leaky”. This concept of intestinal hyperpermeability is well researched, and factors that can increase the “leakiness” of this barrier include chronic stress, alcohol, celiac disease, microbial imbalances and the dietary presence of gluten in genetically susceptible individuals. (1)(2)(3)(4)(5)
The way in which your immune system flags these partially digested proteins (also referred to as “antigens”) is with immune tags called IgG antibodies. It can be helpful to think of antibodies like pieces of ribbon that your immune system ties on to any protein, virus or bacteria that’s viewed as potentially problematic by your immune system.
In lower quantities, these IgG antibodies may actually help your immune system to develop tolerance (and prevent over-reactivity) to the foods in your diet. When present at these low levels, the incompletely digested food proteins that are tagged with IgG antibodies (a.k.a. antigen-antibody complexes) are able to be easily “vacuumed up” by something called our reticuloendothelial system. However, this process can become overwhelmed when when an increased number of undigested food proteins enter into our bloodstream. Instead of being vacuumed up, these antigen-antibody complexes deposit within your blood vessels, organs and joints. This build-up of antigen-antibody complexes causes inflammation that can result in chronic symptoms like those listed above. (6) (7)
Beyond the immediate signs and symptoms of food sensitivities, there is also a growing research demonstrating that intestinal hyperpermeability and chronic immune reactivity may play a role in the development of autoimmune disease. (8) (9) By identifying your food sensitivities and healing any intestinal hyperpermeability or “leaky gut”, you can minimize inflammation and address what is for many people the root cause of their health concerns!
Is IgG Food Sensitivity Testing Science-Based?
IgG antibodies can be measured through an accredited laboratory via a process called an ELISA (Enzyme-Linked Immunosorbent Assay) microarray method. This procedure is often used in scientific laboratories for quantification purposes as it enables proteins, hormones and other molecules to be “tagged” and counted.
With ELISA based IgG food sensitivity testing, the number of IgG antibodies that your immune system has produced in response to each individual food can be counted. Within the laboratory, the process involves introducing your blood sample to a variety of specific food proteins categorized on a gel pad. The number of IgG antibodies that attach to each of these proteins are detected by a scanner, which enables us to identify the degree of immune response you’re experiencing to each specific food. The lab I use in my practice, Rocky Mountain Analytical, uses this process to test for reactivity to up to 220 different foods.
Foods that have an elevated number of antibodies circulating through your bloodstream are indicated as your food sensitivities. I always suggest that my patients confirm this by avoiding the reactive foods for 3-4 weeks so that we can assess whether the avoidance of these foods leads to symptomatic improvement. From there, I’ll often suggest that my patients reintroduce each food back into their diet one at a time to confirm whether the reintroduction of this food indeed triggers their symptoms.
Research that supports the use of IgG Food Sensitivity Testing
The British Allergy Foundation organized a study to follow patients who had recently received an IgG food sensitivity test. The goal was to identify whether avoiding foods that were reported as reactive on their food sensitivity test improved the patients’ symptoms. Over 5000 patients were included in the study, and 70% of those patients rigorously followed the recommendations and eliminated all their reactive foods.
Of those patients who successfully removed the reactive foods from their diets, 76% experienced an improvement in their symptoms and 68% of those patients experienced that improvement within only 3 weeks. Symptom relief varied by body system, with digestive symptoms, anxiety and depression showing the greatest improvement when reactive foods were removed. Of those patients experiencing respiratory symptoms, skin conditions and joint pain, greater than two thirds of these individuals also reported significant improvement in their symptoms. The symptom amelioration was demonstrated to be directly related to the removal of the reactive foods as symptoms returned when the reactive foods were reintroduced back into the diet. The authors concluded that food sensitivity testing is a useful tool for identifying the cause of certain symptoms and the results were published in Nutrition & Food Science in 2007. (10)
I have included a list of these studies in my references at the end of this article, and here is a brief summary of two of those research studies:
IgG Food Sensitivity Avoidance and Weight Loss
Over one hundred overweight men and women participated in an IgG food sensitivity study at the University of Miami Miller School of Medicine. Study participants received blood testing for IgG food sensitivities and voluntarily stopped eating their reactive foods for a period of 90 days. They answered a series of health questions at the 30, 60 and 90 day marks at which point weight and measurements were also taken. The results showed that individuals who stopped eating IgG reactive foods for 90 days lost an average of 1 pound per week. They also lost an average of 3 inches from the hips and 1.5 inches from the waist, plus they reported feeling better physically, mentally, and emotionally. (11)
IgG Food Sensitivity Avoidance and Irritable Bowel Syndrome (IBS)
In a 2004 study that was published in Gut journal, 150 people suffering from irritable bowel syndrome (IBS) volunteered to identify whether food sensitivity testing may help to relieve their IBS symptoms. After completing an IgG food sensitivity test, patients were given a diet to follow. Some received a ‘true’ diet, based on their actual food sensitivity results, while others received a ‘sham’ diet, which did not eliminate any of the reactive foods. The study was double blinded, meaning that neither the patients nor their doctors knew which diet the patient was following. Results of the study showed that the patients who followed the ‘true’ diet experienced significant improvement in their IBS symptoms compared to the patients who had been assigned the ‘sham’ diet. (12)
What are the Advantages of using IgG Food Sensitivity Testing to Identify my Food Sensitivities?
The benefit of using a blood test to identify your food sensitivities is that the process is quick, simple and that it provides you with a detailed report of your immune reactivity to a large number of different foods. Many people also benefit from “seeing their results on paper”, which motivates them to stick to the recommended dietary changes long-term.
An additional benefit is that food sensitivity testing helps us to ensure that reactive foods are not missed when doing dietary-based protocols to identify your food triggers. Evaluating for your food sensitivities via completing an Elimination Diet is a very comprehensive approach, but of course it’s impossible (and undesired) to cut out all potentially reactive foods during the program. Completing food sensitivity testing alongside an Elimination Diet provides for the most comprehensive approach to identify your food sensitivities.
What are the Disadvantages of using IgG Blood Food Sensitivity Testing to Identify my Food Sensitivities?
The downfall of IgG food sensitivity testing is that it won’t identify adverse food reactions that are caused by mechanisms other than IgG antibody production. I describe these other types of food reactions in a recent article, which includes IgE-based food allergies, food intolerances and chemical sensitivities.
The best way to gain clarity on which specific foods are triggering your symptoms is to combine food sensitivity testing with the completion of an Elimination Diet. I often suggest that my patients complete the “elimination phase” of my Elimination Diet Meal Plan online program while we are waiting to receive their food sensitivity lab results. In addition to ensuring that no reactive foods are missed based solely on the food sensitivity report, this also enables people to quickly feel a transformation in their health and energy as their inflammation subsides.
Why you Should Seek Professional Guidance to Interpret the Results of your Food Sensitivity Test
I highly suggest consulting with a naturopathic doctor to help you with the proper interpretation of your test results. It’s important to have someone who is experienced with the assessment of food sensitivities to help you understand your results and to formulate an individualized plan. I have worked with many patients who have had numerous foods reported as reactive, which can be overwhelming to navigate without professional guidance.
If you have elevated IgG antibody production to more than a handful of foods it’s also important that we identify and address WHY this is the case. Often this can be caused by increased intestinal permeability or “leaky gut syndrome”, which I discussed earlier in this article. This syndrome can result from inflammation and imbalances within your small intestine. Celiac disease is one of the many potential causes of leaky gut syndrome, and it’s very important to screen for celiac disease BEFORE you eliminate any reactive foods like wheat or gluten from your diet.
What Other Methods Should I Consider to Identify my Food Sensitivities or Intolerances?
IgG food sensitivity testing is a tool that I use often in my clinical practice, however, an Elimination Diet is my preferred way to help patients to identify their food sensitivities and intolerances. When done properly this enables you to quickly and profoundly improve your health and energy while also identifying your food triggers. You can learn more about how to complete an Elimination Diet by downloading my free eBook series “A Naturopathic Guide to Identifying your Food Sensitivities”. I will also be sharing a brand new blog post on this topic next week!
If you’d like to set up an appointment with me for food sensitivity testing, you can learn more and schedule your consultation here. You can also find a naturopathic doctor local to you who can administer testing through the Canadian Association of Naturopathic Doctors or through the American Association of Naturopathic Physicians.
Have you completed food sensitivity testing or an Elimination Diet before? Either way, I’d love for you to leave your comments and questions below! I read every one of them and always look forward to hearing you.
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