FOOD ALLERGIES, FOOD INTOLERANCES, FOOD SENSITIVITIES – SCIENCE AND COMMON SENSE
July 10, 2019
Most people intuitively appreciate that there is a connection between what we eat and how we feel. I have witnessed this in probably thousands of patients and in myself. Personally, I know if I eat a lot of gluten, I’ll get puffy eyes, dark circles, and feel fatigued. I also know that if I eat tomato & pepper-filled Italian sauce for dinner my joints will be stiff due to accumulation of solanines. Nightshade family vegetables have a lot of this phytochemical and irritates joints, but it isn’t a true “allergy”. The fact that some people have sensitivities to some foods just makes sense. Yet, when we talk about food sensitivities, medically-speaking, the topic becomes a hotbed of critiques on the science. So what’s the deal – science or old wive’s tale? And it is just your imagination, is it becoming more and more common?
“Food allergies” is a label that covers many different physiologic phenomena, ranging from the classical IgE-mediated immune reaction (anaphylaxis) to deficiency of lactase enzyme termed lactose intolerance. There are people who have frank celiac disease; characterized by autoimmune attack and destruction of the cilia of the intestines. And there are people who have a different type problem with gluten characterized by an enzyme deficiency (DPP-4, specifically) that prevents them from breaking down proteins in gluten. While immunologically, these conditions have different causes and may have different symptoms, both people will be healthier if they follow a gluten-free diet. So will people who have other types of immune reactions which could include IgG antibodies to gluten-related molecules, like wheat bran. Additionally, immune reactions can occur to patient’s own tissues, such as their cerebellum, because of auto-immune cross-reactivity with gliadin antigen (Datis Kharrazian, DC has expertly summarized this body of research). All of these phenomena can be labeled “food allergies” and can be tested for, albeit with varying degrees of predictive power. I’ll review the testing options specifically for Celiac and gluten in a future blog.
So, where should one start if they want more information about foods they may be potentially sensitive to? Three major options exist: get tested for immune-mediated food sensitivities with a blood test, get tested for non-specific food intolerances with a electrodermal bioimpedance system, or conduct your own experiment with an Elimination and Re-Challenge process. Here are some of the pros and cons of each.
Blood tests for food sensitivities typically cover a panel of 50-150 different foods and test for immunologic reactions, specifically whether your white blood cells produce IgE, IgG, or IgA in response to exposure to the food antigen. You can read about the scientific differences between these types of antibodies here, but the short of it is this:
IgE antibodies trigger immediate anaphylactic-type reactions through triggering the release of histamine from mast cells. Anti-histamines, like Benadryl or an Epi-Pen stop these reactions. Bioflavonoids like quercetin, hesperidin, and vitamin C reduce the mast cell reactivity. More on treating food sensitivities later.IgA antibodies are primarily located in mucosal tissue, like the digestive system and genitourinary tract. Having a strong localized IgA response to prevent bacteria or viruses from colonizing our systems, but having a localized response to a food particle doesn’t necessarily make sense.IgG antibodies are the most common ones in the body and take care of most of our immune responses, to viruses, bacteria, mutant cells, food particles, and sometimes to our own tissues (like in auto-immune disease). These are also called delayed-immune responses because it takes the body 24-72 hours to make sufficient IgG to respond to the invader.
Depending on your symptoms, you and your doctor may want to test for different types of Ig responses. If your symptoms are non-specific, a comprehensive IgG food panel is a good place to start.
However, I always advise my patients that test results are just information. Using the results from the testing, it is best to proceed to a month-long elimination of the reactive foods. See how you feel. Without constantly introducing foods that cause the immune system to produce antibodies, the immune system can quiet down and symptoms typically improve. After a month, you may want to conduct the Re-Challenge phase of the experiment. More on that later.