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Should you get a Food Sensitivity test?

Food sensitivity testing is a subject that is near and dear to my heart. I have been studying the various aspects of how our bodies react to foods for over 20 years and will share with you here some of the more important principles I have learned. Most of this comes from actual clinical experience with patients as the science on food sensitivity testing is controversial, which I will explain further in this blog.

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First of all, let’s get a common language for the concept of food sensitivity testing. Most lay people use the terms “food allergy” and “food sensitivity” or “intolerance” interchangeably. From the standpoint of human physiology, and what your doctor understands about the topic, a “food allergy” is a specific type of food sensitivity. Medically, an allergy is a group of symptoms ranging from hives, itching skin or eyes, and nasal congestion to swelling of the tongue, closing of the throat, or even anaphylaxis, which is complete collapse of the cardiovascular system. Although relatively rare, anaphylaxis is life-threatening. This is the person who cannot get near even a trace of certain foods, such as peanuts, without beginning the immune system cascade based upon immediate reactions of the immunoglobulin IgE (a type of antibody). These reactions can be diagnosed with skin prick testing by an allergy specialist. This person should carry epinephrine injections with them in case of an unexpected exposure, and must avoid ALL exposures to the offending food, even trace amounts.


Most food sensitivities, however, are very common, and not life-threatening, at least in the short-run. They represent many diverse reactions of the body, both immunological, such as inflammation, and not involving the immune system, such as hormonal. This is where the confusion often comes in. When we begin to pay close attention to our bodies, noting changes from our usual health, we can become aware of symptoms ranging from sleep difficulty to blood pressure elevation to joint swelling and even more serious diseases all related to food sensitivities or intolerances. As will be described below, you can even use small changes in your pulse rate to help you determine food sensitivities. But first, let’s talk more about food sensitivities with some examples.

Often, people expect that food-related symptoms will show up with something affecting the digestive tract. While this is often the case, it is by no means universal. I see people every day who have undiagnosed food sensitivities which they do not even perceive because they have no digestive complaints. This can range from rashes to sleep disruption to inflammatory arthritis to brain fog, poor concentration or even depression. Certainly, any gastrointestinal (GI) complaint may be related to food intake and bears investigation of which foods are contributing. The same principles apply whether your symptoms affect the gut (anything from the mouth to anus) or lie outside the GI system.


In our technologically-based culture, we have become dependent on laboratory tests to give us answers to what is going on inside out bodies. Nonetheless, I am a strong proponent of learning to listen to your own body for clues, as we will discuss below. Still, because most people want quick, simple answers (even when they don’t address true root causes) let’s start with the pros and cons of some of the available food sensitivity testing. While it may be helpful to use some of these tests to help you narrow the field about possible food choices, you must realize that a test printed in three colors with pages of explanation does not cover all possible ways your body may be reacting to what you eat. Just because it is printed in multiple colors with scientific-sounding explanations, does not make it the have-all-and-be-all diagnosis of what is going on inside your body.

Skin prick testing, and certain blood IgE testing, such as RAST or ImmunoCAP Specific IgE blood tests are designed to test medically-defined IgE allergies (as described above). These tests are often covered by medical insurance. While reasonably accurate for true allergy reactions, just because a person does not react to certain foods on these tests, does NOT exclude the possibility of other types of food sensitivities. True allergy testing looks at more immediate-type reactions, but does not detect more delayed reactions. The immune system is elegantly complex, and many different aspects of its reactions can be seen with various types of testing. The most important question, however, is whether the results of these tests help us to know which foods to eat and which to avoid. That is, do the tests have lots of false positives or false negatives. Unfortunately, in the food testing department, these false results are all too common. Studies have taken samples of blood from the same person on the same day and sent them for different types of testing, only to find completely different results. This is because there is no one test that can accurately predict every type of reaction a whole human body can have. Like a ship whose components would sink if not constructed together, your body is much more than a sum of its parts. We try to take the systems apart to study them, but never forget that you, as a whole person are awesomely unique.

Before you spend your hard-earned dollars on testing which may or may not help you decide what to eat, let’s look at some common food sensitivity tests as well as their pros and cons.

  • IgA/IgG testing. Available from many laboratories, including Genova, US Biotek, Great Plains Lab, KBMO Diagnostics, and others. This is a blood test that looks at more delayed reactions of the immune system. Some IgG reactions can be delayed as much as four days, which will be discussed below concerning elimination diets. IgA/IgG testing does not test for true allergies, as described above. It also does not test for any other possible reactions of the immune system. Again, it can provide some information, but does have false negatives and positives.

  • ELISA/ACT test. Using a type of white blood cell called lymphocytes, this test looks at reactions to foods, herbs and other supplements. Again the rate of false positives and negatives has found to be significant.

  • LEAP/MRT test. This blood test looks at a wide range of possible inflammatory mediators in the immune system which may be triggered by foods. While inflammation is one of the most common forms of food sensitivity, no one test looks at every way the immune system reacts, again leaving us wondering if it is truly answering the questions of what is safe to eat.

  • Cyrex labs tests. Cyrex labs uses food sensitivity testing technology evolved over nearly 40 years. Their different “arrays” can help distinguish up to 17 different ways your body may react to gluten (much more than standard genetic or antibody testing.) They can also help determine if foods completely unrelated to gluten, such as potatoes or dairy products are triggering gluten receptors in your body. Helpful to answer these specific questions, their testing can look at multiple ways your immune system may be reacting to foods. Still, the tests cannot cover all possible ways you may be experiencing food sensitivities.

Many other lab tests exist in addition to those mentioned, but there is no single test that answers our questions about what foods may be contributing to a particular symptom or diagnosis. And, even more confusing, doing a combination of tests may give conflicting results, so interpretation by a trained health professional is required to get the most benefit. Still, when stuck on what one must do to get well, these and other tests can be helpful to give us clues. Just be aware that are not definitive.

So, you still want something that can reliably tell you “Eat this, not that”. This is where we can completely rely on your own body to tell you what it needs and wants. There are two completely free tests you can do at home to give you more clues. They require a little more time and personal investigation, but, most importantly, you can trust them. Your body does not lie. Learning to listen to it, and honor its signals can take some practice, and it is well worth the effort. Note, for both of these tests, testing foods separately is key as any contaminant may be confusing. For instance, if you are testing wheat and eat a cereal with milk on it, even almond milk, it can confuse whether your reaction is to the wheat, the milk or something else eaten at the same time.


The first test is called the Pulse Test, described by Arthur Coca, MD in his book The Pulse Test. Based upon reactions of the sympathetic nervous system, which signals fight or flight, the test shows you how to take your pulse when you sample a certain food. If your body deems a certain food to be threatening, it will make your pulse rate go up, cluing you in to the fact it does not like that food. Find some simplified versions and the original steps described in a handout here under Diagnostics for Dummies.

A more comprehensive method of identifying food triggers to your health is called the Elimination Diet. Many versions of the Elimination diet abound, and all involve eliminating most common food sensitizers for two weeks at minimum, then re-introducing one food at a time and noting reactions. It takes up to two weeks for certain antibodies to be cleared from your system, and some inflammation or other symptoms may need a month to noticeably heal.

There are some important considerations for getting the most from this process. First, you need to give your body some time to heal after stopping certain foods so that you can notice if there are any differences when you re-introduce foods. This is absolutely key. You must pay attention to what you body is telling you all over, not just in the symptom you are concerned about. The food that made your eyes itch, or the night you wake up several times, a random joint discomfort, even smelly gas can all alert you that your body is reacting to certain foods. While it can take several months for serious symptoms from autoimmune or other diseases to resolve, often little things such as less indigestion or no headaches can help us recognize we are on the right path. You will need to make some sort of spreadsheet, or at least use a calendar to note when foods are stopped, reintroduced and your reactions. There are also some apps, such as Allergy Journal Android, Food Allergy Detective, Doc's Diet Diary. (I have not evaluated these and would appreciate your feedback about what you find most useful.) Again, testing foods individually, as noted above, is key.

Sorting out food sensitivities is a big challenge, and oh-so-worth-it. Ask the patients whose swollen joints now bend without pain, who no longer need medication for esophagitis, who heal from serious diseases such as multiple sclerosis, or who are no longer depressed. It took a week for my headaches to resolve once I gave up the last precious “cheat treat” I still ate containing peanuts. It took several months more for other signs of inflammation in other areas of my body to resolve. And it is well worth feeling great every day.

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