Ever hear of food sensitivity testing? Intrigued by it? Considering asking your medical team about it?
Food sensitivity tests go by many different names. IgG, MRT, LEAP...the list goes on. These tests are very popular right now, and may seem like the right next step to take in terms of your IC treatment.
If you haven't been living under a rock the past few years, you’ve already heard about food sensitivity tests. Perhaps you’ve seen them advertised on social media, were recommended to get a test done by a chiropractor/naturopath/other medical professional, or you know a family member or friend who has had one of these tests done.
What are food sensitivity tests?
These tests generally require a blood draw, saliva, or hair follicles. Some of these tests can be ordered by physicians or registered dietitians or you can order one on the internet and have it shipped to your house - how convenient! A test that can tell you what not to eat in order to eliminate your IC symptoms - what else could you ask for?
As a registered dietitian/nutrition coach who works with people with IC, you would think I would support testing that can identify food intolerances. But it’s quite the opposite, actually.
The problem with these tests are they usually lead to over-restriction. Any person I work with that has had a food intolerance test done in the past is usually following a restrictive diet by eliminating all foods that were identified in that test of not being tolerated by their body.
To give you an idea of what a typical experience with a client who has had food sensitivity testing done before they meet with me, here goes….
We get on the call (you know, because of Covid), and they tell me about all of the foods they tested positive as being sensitive to. This is usually an extensive list of foods that the typical person consumes on a daily basis. They discuss how difficult it is to avoid all of these items as a lot of them are staples to their daily life. Sometimes they end up feeling better after eliminating these dietary “offenders”, but usually they end up admitting how upset and worried they are at the idea that they have to eliminate these foods forever. This is where I come in to save the day!
Food Allergy vs. Sensitivity
Let’s first identify the difference between a food allergy and food sensitivity.
A glass of milk may leave you with symptoms of nausea, cramping, and fatigue - is this an allergy or an intolerance?
A food allergy is an immunologic response to an allergen that results in reproducible symptoms with every exposure. A food allergy involves the immune system. Signs of a food allergy include skin rashes, swollen tongue, breathing problems, dizziness, fainting, hives, nausea, and many other symptoms. What is happening in your body is, when an allergen such as a peanut enters the body, your immune system sees it as a threat and releases a bunch of histamine. This crazy reaction is actually your body’s way of trying to protect you!
A food sensitivity has no standard medical definition. A food sensitivity or intolerance is a non-immunologic response to a food that takes place in the digestive system. Food sensitivity testing measures the IgG antibodies the immune system creates in response to proteins found in certain foods. Basically, you take a blood test, wait a few weeks, and receive a list of foods that you are “sensitive” to. And you are basically expected to just eliminate all of these items.
Let’s take a look at the various testing methods and their accuracy.
Food allergy tests
Skin prick test (SPT): usually done in an allergist’s office, you are pricked in the skin and a specific allergen is applied to the area. They can actually test for up to 40 different allergens at one time. Positive results are indicated by a wheal – a raised white bump surrounded by a small circle of itchy red skin. Food Allergy Research and Education reports that positive tests are not always positive, and about 50-60% of all SPT yield "false positive" results. Despite the higher level of "false positives", this type of test can be helpful for experienced allergists in determining a treatment plan for a patient.
Blood test (RASTs): also detects allergic reaction to a food, just takes a bit longer to get the results. Also have 50-60% "false positives".
Common food sensitivity tests
IgG Antibody testing: Immunoglobulin G, or IgG, is produced by the immune system whenever a foreign substance is detected - it could be food or an environmental allergy, like pollen or pet dander. Recent studies are not finding any connection to a food sensitivity when a high level of IgG is detected. It is becoming apparent that IgG antibodies ar ea measure of exposure to a certain food, and possibly, tolerance! Isn’t that ironic? For example, let’s say you had dairy the day before your IgG test. Dairy will most likely come up as positive for sensitivity because you had consumed it the day before, and it is still in your body. This type of testing does not show sensitivity, it shows exposure.
Brand example: Everlywell
Mediator Release Test (MRT®): This blood test measures your sensitivities to 170 different foods. This test can cause anywhere upwards of $400. This test is actually done by some Registered Dietitians still. However, In 2016, the Commission of Dietetic Registration discontinued its support for it due to insufficient evidence for using it for diagnosis of food intolerances.
Hair follicle test: Producers of this type of test claim to identify food sensitivities, nutrient deficiencies, and metal toxicities.
The research is showing, however, that this type of test is not a valid diagnostic tool for determining food intolerances or nutrient deficiencies (although it can actually detect metal toxicities).
Electricity testing: One popular test is called the Vega test, also referred to as electrodermal testing. It operates on the principle of bio resonance. Basically, it measures changes in the amount your body conducts or resists electricity, or impedance. This type of test has no scientific evidence or reasoning for identifying food allergies or sensitivities. One thing it CAN do is determine % body fat.
What do all of these tests have in common?
They convince you that you have a problem
They support a restricted diet
They are NOT backed by science
What you must know moving forward is that there are ZERO validated tests to evaluate for or diagnose food sensitivity. I’m sorry to tell you this, but you wasted your time & money on these tests. I'll say it again - there is no credible evidence supporting these tests at this time.
If you’re reading this and had food sensitivity testing done, you may be thinking, so what now? The good news is, these tests won’t usually harm your body. The results are most likely just inaccurate.
For those of you reading this that haven't had a food sensitivity test done: keep in mind that FEAR SELLS. These tests create problem, or a "fear" of certain foods. Bottom line: do not waste your money on these tests.