Index
Sometimes certain foods can make you feel bad, regardless of whether you are healthy.
They can trigger food sensitivity symptoms, such as headaches, digestive problems, joint pain, or skin problems.
It can be challenging to determine which foods are responsible, as food sensitivity reactions are often delayed for a few hours or more after eating.
To help identify potential problem foods, some health professionals offer food sensitivity tests.
Here’s what food sensitivities are and the best tests to identify them.
Food sensitivities
Three different terms are commonly used for adverse reactions to food: food allergy, food sensitivity, and food intolerance. However, not everyone defines these terms in the same way.
The term food allergy is best reserved for food reactions that can be life-threatening and involve immunoglobulin E (IgE) antibodies from your immune system. These are “true” food allergies.
In contrast, food sensitivities and intolerances are generally not life-threatening, but they can make you feel unwell.
Summary
A true food allergy is a life-threatening reaction that involves IgE antibodies from your immune system.
Food sensitivities involve other antibodies and cells of your immune system, while food intolerances do not affect your immune system.
Elimination diet and challenge test
The gold standard for identifying food sensitivities is an elimination diet followed by an ‘oral challenge’ of eating the eliminated foods one at a time after a period of avoidance to determine your reaction, ideally without you knowing what is being tested.
If you do not follow an elimination diet before the oral food sensitivity challenge, your symptoms in response to consuming a food antigen may be masked or challenging to detect.
When you stop eating a problem food, you may have temporary withdrawal symptoms. You may need to be on an elimination diet for about two weeks before these symptoms go away and you are ready to start tasting foods in an oral challenge.
Following an elimination diet requires dedication and commitment, and careful registration. You need to know the ingredients in everything you eat, making it challenging to eat out.
The foods you avoid on an elimination diet vary. Some professionals may only ask you to eliminate foods suspected of being a problem, such as dairy and wheat.
Others may ask you to eliminate all but a few foods for a short period, such as two weeks, and then slowly reintroduce them.
To reduce the guesswork about which foods are problematic, some professionals first perform a food sensitivity test to help guide your elimination diet.
Importantly, you should never attempt to reintroduce a food on your own if you have a true allergy. If you suspect that you may have overcome a food allergy, discuss the appropriate tests with your allergist.
Summary
The gold standard for identifying food sensitivities is an elimination diet followed by a systematic “oral challenge” of tasting the eliminated foods after avoidance.
Some practitioners use food sensitivity tests to identify problem foods.
Cell-based tests
Cell-based tests for food sensitivity began with the cytotoxic test, which became popular in the 1950s. Several states banned this test in 1985 due to problems with its accuracy.
Since then, immunologists have improved and automated the testing technology. Two available cell-based blood tests are MRT and ALCAT.
Although some practitioners have reported that they find these tests helpful, the published studies of the tests are limited.
Mediator Release Test (MRT)
The MRT requires a blood sample, usually drawn from a vein in the arm and collected with a kit from the company that has a patent on the test.
If your white blood cells ‘shrink’ when exposed to a food antigen in the MRT test, there is a change in the ratio of solids (white blood cells) to liquid (plasma) in your blood sample, which is measured to determine your reactivity to food.
When your white blood cells shrink from being exposed to a food antigen, it suggests that they have released chemical mediators, such as histamine and leukotrienes, that could cause symptoms in your body.
The diet based on your MRT results is called LEAP (Lifestyle and Performance) and is led by healthcare professionals, such as dietitians trained in the test and its interpretation.
A small study presented at an American College of Gastroenterology conference found that people with irritable bowel syndrome (IBS) who followed an elimination diet based on MRT results for at least a month reported a 67% improvement in intestinal problems such as diarrhea.
However, there was no control group in this study, nor has it been published in its entirety. Also, PubMed, an extensive database that indexes published medical studies, does not show studies on the MRT test.
Antigenic Leukocyte Cellular Antibody Test (ALCAT)
The ALCAT test is the predecessor of the MRT test, but many healthcare professionals and laboratories still offer it.
To assess which foods may trigger a reaction, it only measures changes in the size of your white blood cells (rather than changes in the ratio of solids to liquids) when exposed to individual food antigens, which can decrease accuracy.
When people with IBS followed a diet based on their ALCAT tests for four weeks, they reported twice the reduction in specific IBS symptoms, such as abdominal pain and bloating, compared to people who followed a placebo diet.
However, those who followed ALCAT-based diets did not rate their IBS relief as adequate or significantly improving their quality of life during the study.
Summary
Cell-based blood tests, including the MRT and ALCAT, assess changes in your white blood cells when exposed to food antigens.
Some professionals report that the tests help identify food sensitivities, but both require further study.
Antibody-based tests
Antibody-based food sensitivity tests measure your production of immunoglobulin G (IgG) antibodies to food. They are available under various brand names.
This type of test has more published research than other food sensitivity tests, but the studies are still limited.
These studies suggest that eliminating foods guided by IgG tests can help improve symptoms in people with IBS and migraines.
However, many scientists advise people not to use IgG food sensitivity tests, saying that IgG antibodies to food may show that you have been exposed to food.
In some other cases, they may be protecting against allergic reactions to food.
However, other scientists say that it is not normal for someone to have high IgG antibodies against food.
Another concern is that individual lab tests for IgG develop their in-house techniques. Many have poor reproducibility, which means that if the same blood sample is tested twice, it can show very different results.
You should only use an IgG test if you test your blood sample twice with each antigen in the side-by-side duplication test to minimize errors in your results.
The bloodstain test is a variation of the traditional IgG test that requires a phlebotomist to draw blood from a vein in the arm. Instead, it uses a small blood sample from your finger collected on a particular test card. It is unknown if this method is reliable.
Summary
Tests that assess your food IgG antibody levels are available under various brand names and can help identify foods involved in symptoms such as IBS and migraines. Accuracy is improved if a lab runs duplicate side-by-side tests.
Other tests
Some alternative practitioners, such as chiropractors, naturopaths, and environmental medicine doctors, may use other tests to check for food sensitivities.
Muscle response tests, provocation tests, and electrodermal screening are some of the more common options.
Muscle response test
Also known as applied kinesiology, muscle response testing involves holding a vial containing a food antigen in one hand while extending your other arm parallel to the floor.
The practitioner then pushes down on his outstretched arm. If you push down quickly, indicating weakness, you are told that you are sensitive to the foods being tested.
The few published studies of this method were no better at identifying food sensitivities than what would be expected by chance.
It is unknown to what extent the precision of this method varies with the individual skill level of the practitioner.
Provocation and neutralization test
In this test, individual food extracts suspected of causing reactions are injected under the skin, usually in the upper arm.
After 10 minutes, a check is done to see if a “welt” or raised swelling forms, suggesting a reaction to the tested food.
If a welt forms, a second injection of the same food is given but in a dilution that is five times weaker than the initial dose. This is given to try to neutralize the reaction.
It is rechecked after 10 minutes. If there is no skin reaction, the administered dose is considered your neutralizing dose.
It may take several progressively weaker dilutions to find the neutralizing dose. He can be taught to give himself injections regularly to desensitize him to that food.
When people were given provocation skin injection tests for five food sensitivities previously confirmed by oral examinations, the results were in agreement 78% of the time.
Given the number of injections you must receive as part of this test; it could be a slow and potentially painful process.
Electrodermal screening
This test measures your skin’s electrical activity changes at acupuncture points when various food antigens are presented to you.
You hold a brass tube (an electrode) in one hand for this test. The line is connected to a computer containing digitized frequencies of individual foods. A professional presses a probe connected to a computer to a specific point on the other hand.
Based on the electrical resistance of your skin when challenged with each food digitally, a numerical reading is generated that corresponds to your degree of reaction to the food.
No published study has evaluated this technique to test food sensitivities.
Summary
Muscle response tests, provocation tests, and electrodermal screening are additional types of food sensitivity tests.
These generally take longer than tests based on a single blood draw. Furthermore, studies of its validity are limited or non-existent.
Precautions
Food sensitivity tests come with several caveats. Most importantly, the tests are not designed to be used to diagnose true food allergies.
If you have a diagnosed food allergy, such as peanuts, you should continue to avoid it, regardless of your results on a food sensitivity test.
If you consider using these tests to identify food sensitivities, keep in mind that they are not deemed to be proven, so insurance companies may offer little to no coverage. Many of the tests cost several hundred dollars.
Also, to verify the accuracy, any food sensitivity test results must be cross-checked with what happens in your body when you eat the food.
One possible reason for the discrepancies is that most laboratories that perform food sensitivity tests use primarily raw food extracts.
However, new antigens can be created when food is cooked or processed, and existing antigens can be destroyed.
The purity of each food extract (antigen) used by some laboratories also varies, altering the results.
Also, keep in mind that food sensitivities can change over time depending on what you’ve been eating. A test done six months or a year ago may not reflect your current reactivity to specific foods.
Following outdated or inaccurate food sensitivity test results could lead to unnecessary dietary restrictions, potential nutrient deficiencies, and decreased quality of life.
Finally, scientists and healthcare professionals have more to learn about food sensitivities. Testing and treatment will continue to evolve with ongoing analysis.
Summary
Food sensitivity tests cannot be used to diagnose true food allergies.
Although some can help identify food sensitivities, insurance companies often do not cover testing. Several factors can affect the validity of test results, and sharpness can change over time.
The bottom line
- An elimination diet followed by methodically testing the eliminated foods one by one after a period of avoidance is the best way to identify food sensitivities.
- Laboratory tests, such as the MRT, ALCAT, and IgG antibody tests, have limitations, and their accuracy may vary by laboratory. However, they can help reduce the guesswork.
- Still, these tests have not been compared to each other in published, controlled studies, so it is unknown whether one test is better than another.
- If you suspect that you have adverse reactions to food, start by consulting your doctor, who may refer you to a gastroenterologist, allergy doctor, or other professional for guidance.
