The Role of Food Sensitivity Testing
Testing for food sensitivities is done after a person has had symptoms of an adverse food reaction. Based on the symptoms and the foods consumed before they occurred, tests can be ordered to look for specific food allergies, intolerances, or sensitivities. In this way, food sensitivity testing is a tool for diagnosis, helping to identify foods that provoke an abnormal reaction.
It is uncommon to do broad screening for food sensitivities, especially if you haven’t already had signs or symptoms of a food reaction.
Who should get testing?
It is generally recommended to only test for food sensitivities or intolerances after you have experienced symptoms of a potential problem. Some common testings include gluten and lactose intolerance testing.
If you haven’t had symptoms, food sensitivity testing is likely to have more downsides than benefits. No test exists that can accurately detect all food sensitivities. Testing for a wide range of possible reactions can return a false positive, which means the test shows an intolerance or sensitivity for a food that doesn’t actually cause you problems. False positives can cause unnecessary changes to your diet that may affect your nutrition.
If you’ve had signs of a food reaction, talk with your doctor. By reviewing your experience and symptoms, the doctor can describe the pros and cons of testing for specific allergens, intolerances, and/or sensitivities.
Types of Food Sensitivity Tests
No single, comprehensive test is available to check for all or even most types of food sensitivities. As a result, tests are typically tailored to match your symptoms and health history.
Because there can be symptom overlap between food sensitivities and food allergies, the doctor may recommend a skin prick test or blood allergy test to be sure that you don’t have a food allergy.
Unfortunately, tests cannot easily identify most food sensitivities. However, some specific intolerances can be found with testing:
- Lactose intolerance, which is the inability to properly digest a type of sugar found in milk products, can be detected with lactose tolerance tests. These include blood or breath tests that demonstrate disrupted lactose digestion.
- Celiac disease is a disorder in which a person’s immune system attacks their intestinal lining when they consume gluten, a protein found in wheat and other grains. Blood tests can help diagnose celiac disease by analyzing levels of specific antibodies, which are proteins produced by the immune system.
Some people are intolerant of gluten without having celiac disease, and this is often referred to as non-celiac gluten sensitivity (NCGS). There is no test that has been validated to accurately detect NCGS.
For most other food intolerances and sensitivities, there is no reliable test to detect them. As a result, a doctor may suggest other types of tests:
- Oral food challenge: This involves eating increasing quantities of a food over a period of hours while being closely monitored for adverse reactions. Oral food challenges follow a specific protocol and should only be done in a controlled medical setting.
- Food elimination diet: This requires following a strict diet that excludes specific foods or additives for a period of weeks. Over time, the dietary restrictions may be modified to try to identify specific intolerances or sensitivities.
People with symptoms of food reactions may have testing for other conditions such as inflammatory bowel disease, irritable bowel syndrome, or malabsorption of nutrients. Examples of tests related to these conditions are listed in the table below:
| Test Name | Test Sample | What It Measures |
|---|---|---|
| Xylose Absorption | Blood and urine | How well the body absorbs a simple sugar |
| Fecal fat | Stool | Amount of fat in a stool sample |
| Erythrocyte Sedimentation Rate (ESR) | Blood | Rate at which certain red blood cells fall when blood is placed in a test tube |
Many tests that are marketed for detecting food sensitivities and intolerances have not been proven to be accurate or effective, and experts recommend against using them. Examples of unvalidated tests include:
- Immunoglobulin-G (IgG and IgG4) antibody tests
- Hair tests
- Blood cell analysis, including flow cytometry and mediator release tests
- Provocation or neutralization testing
- Electrodermal testing
- Muscle reaction or strength tests
Getting Tested for Food Sensitivities
Food sensitivity testing is normally conducted in a doctor’s office, clinic, or medical laboratory. The procedure depends on the specific test being used. Tests are prescribed by a doctor after reviewing your symptoms to determine the most probable sensitivity or intolerance.
At-home testing
At-home testing is available for certain types of food sensitivities. Some tests for lactose intolerance and celiac disease can be done with at-home kits to obtain a blood sample that is then sent by mail to a laboratory. A positive result on at-home testing usually requires follow-up tests prescribed by a doctor.
Some tests are available that look for dozens of types of antibodies called immunoglobulin-G (IgG) in the blood. However, experts advise against this type of screening because it has not been shown to be accurate in identifying true food intolerance and sensitivities.
If you are concerned about a possible food sensitivity, it’s important to discuss your symptoms with your doctor to determine the most appropriate tests in your case.
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