MRT Test: Can a Blood Draw Discover Food Sensitivities?

The last thing you want to experience when enjoying your favorite food is to experience mild allergic-type reactions hours later – itching, flushed skin, brain fog, sneezing or headaches. For some people, though, these symptoms can occur as part of a food sensitivity. Food sensitivities, unlike food intolerances and food allergies, haven’t been studied as extensively, leaving many people searching for solutions.

One of these potential solutions is the development of tests that claim to identify foods you may be sensitive to. Can these tests, including one called a mediator release test (MRT), provide insight or do they just lead to confusion? This blog will help explain the latest developments.  

Analyzing different types of food reactions

Whether it’s a food allergy or a food sensitivity, there are many types of reactions the human body can experience when eating or coming into contact with foods. 

There tends to be confusion among the uses of “intolerance” and “sensitivity,” so the following is a breakdown of the difference between food allergies, food intolerances and food sensitivities. 

Food intolerance

A food intolerance is the inability to process or digest a food or a certain type of ingredient. Symptoms include gastrointestinal problems such as diarrhea, nausea, abdominal pain, gas and bloating. You may feel discomfort within a few hours of eating the food that causes the intolerance, although you may not experience any symptoms when consuming a small amount of food.  

Lactose intolerance is one of the most common types of food intolerances. People who are lactose intolerant don’t have the enzyme needed to break down lactose. As a result, undigested milk sugar causes stomach and intestinal problems. 

Food allergy

A food allergy, by contrast, occurs when the immune system mistakenly perceives food (a protein, chemical or other food additive) as a threat against the body and causes an allergic reaction. Unlike a food intolerance, a food allergy strikes quickly in a matter of seconds or minutes. Hives, shortness of breath and swelling are common symptoms. In more severe cases, an allergic reaction can cause anaphylactic shock, a life-threatening condition that leads to a drop in blood pressure and swelling of the bronchial tissue.

Egg, dairy, peanut, tree nuts, fish, shellfish, wheat, soy and sesame are the most common types of food allergies. 

Food sensitivity

Within the medical community, there is debate about the word food sensitivity and there isn’t a standard agreed upon definition.  

Some people view food sensitivities as a slower immune response, likely due to a bacterial imbalance in the GI tract. 

Others lump food intolerances and food sensitivities together. For example, some view lactose intolerance and dairy sensitivity into the same group. But lactose intolerance involves the inability to digest milk sugar, whereas a dairy sensitivity is a mild immune response to proteins in cow’s milk. 

Food sensitivities shouldn’t be confused with food allergies, though. During an allergic reaction, the immune system produces antibodies called Immunoglobulin E (IgE). By contrast, food sensitivities trigger the production of a different type of antibody known as immunoglobulin G (IgG). This difference causes a slower, more gradual response that can take hours or days to present symptoms. 

Non-celiac gluten sensitivity is one of the most common types of sensitivities. This occurs in people who have similar symptoms of celiac disease (an autoimmune disorder) when eating gluten but test negative for the disease. Food sensitivities can also occur when eating dairy, eggs, corn, soy, tree nuts, legumes and citrus fruits. 

MRT food sensitivity tests

Since there are so many different foods that can cause adverse reactions, it can be difficult to narrow down the root of the problem. For years, healthcare professionals have used elimination diets to identify the source. 

More recently, biotech companies have created several types of food sensitivity tests. Of the tests, the mediator release test (MRT) has received the most traction in the medical community. When the immune system encounters foods, it releases pro-inflammatory chemicals called mediators.  

Using a blood draw, MRT combines a blood sample with food extracts in a test tube to identify changes from white blood cells (lymphocytes, neutrophils, monocytes and eosinophils) to isolate foods, chemicals or additives that cause inflammatory reactions. The idea is foods or ingredients with a high IgG level can be eliminated from your diet and provide symptomatic relief. 

MRT can test for more than 150 foods and additives, including chemical sensitivities such as MSG, fructose, aspartame and artificial colors. 

MRT tests don’t test for allergens since it looks at IgG reactions and not the IgE reactions caused by a food allergy. 

The Antigen Leukocyte Antibody Test (ALCAT) test is another common type of blood test that measures food sensitivities. Like the MRT test, ALCAT incubates a specific type of white blood cell called leukocytes in test tubes with food extracts to detect sensitivities.  

The ongoing debate over food sensitivity testing

Despite tests such as MRT that are marketed as a way to identify food sensitivities, none have been validated through rigorous testing. As such, the American Academy of Allergy, Asthma & Immunology and the Academy of Nutrition and Dietetics don’t support food sensitivity tests.  

The reasoning, they say, is a lack of evidence. For example, they contend IgG antibodies are produced by many people after eating certain foods, meaning they aren’t always indicative of a food sensitivity.  

There are also concerns with price and the unintended consequences of sensitivity tests leading consumers down a rabbit hole and into unhealthy eating habits.  

The tests can cost hundreds of dollars and are best suited when combined with a dietician or nutritionist consultation. The goal of MRT testing is to identify which sensitivities may be causing symptoms and to create dietary changes with the help of a dietician. Plus, due to the lack of backing by credible institutions, insurance companies usually don’t cover food sensitivity testing.

As for eating habit concerns, sensitivity tests may confuse consumers by identifying dozens of possible culprits as the source of their symptoms. This can create anxiety about food choices when deciding what to eat and what not to eat. It may also lead to misdiagnosis.  

The bottom line of food sensitivity tests

There are some physicians who are proponents of food sensitivity tests, especially for patients with irritable bowel syndrome. In 2021, the American Journal of Gastroenterology even acknowledged the results of leukocyte activation tests, such as those performed by ALCAT, “are intriguing but need to be confirmed.” 

So while they may have a role in helping people identify foods that cause symptoms, ultimately there isn’t a consensus on the effectiveness.  

What should you do then? For starters, visit your primary care physician and explain your food-related symptoms. They will likely refer you to an allergist to rule out a food allergy or have you meet with a gastroenterologist to discuss possible food intolerances or sensitivities. 

Many doctors recommend an elimination diet to help narrow down the cause of your symptoms. With an elimination diet, you remove foods that may be the culprit for several weeks and then slowly reintroduce them to see which foods, if any, cause symptoms. A dietician or nutritionist can help guide you along your journey. For more tips, read our blog on how to do an elimination diet.