Are Food Sensitivity Tests Accurate?

Are you considering a blood test to see if you have a food sensitivity? Maybe you’re surprised to find out your insurance company will not pay for the test. After all, isn’t it a medical test?

A food sensitivity is not an official medical diagnosis. This term, however, is used by the makers of various blood tests claiming to detect sensitivities to certain foods. The reality is that there’s limited evidence to suggest these blood tests are able to do what they say.

What’s the Difference Between an Allergy, Intolerance and Sensitivity?

Food allergies happen when the immune system reacts to a substance in a food or group of foods. Typically, the immune system goes into gear when it detects a harmful substance. It does that by making antibodies to fight it off. This results in a range of symptoms, which can include skin rashes and breathing problems.

Food intolerances are not an immune system reaction. They relate to trouble digesting foods. Food intolerances occur when a person lacks the specific enzyme needed to digest certain foods or compounds in foods, like lactose (a natural sugar in milk). Individuals with food intolerances may be able to eat small amounts of bothersome foods. But, when they have too much, their body reacts. For example, many people with a lactose intolerance find they can drink a small amount of milk with meals or eat yogurt or other foods that are lower in lactose without experiencing any symptoms.

Food sensitivity has no standard medical definition. It can be used to mean a range of things. Sometimes, this term is used instead of food intolerance, such as a sulfite sensitivity and histamine sensitivity. Other times, it is used as a catch phrase that includes both food allergies and intolerances.

If you think you might have a food allergy or intolerance, talk with your health care provider. Discuss your symptoms so that other possible conditions can be ruled out first. This is especially true for celiac disease, since it can result in damage to the small intestine. In some cases, people who experience symptoms similar to those of celiac disease, but test negative for it, may be told they have non-celiac gluten sensitivity (NCGS). Research is limited and currently there is no specific test for gluten sensitivity. Some individuals with NCGS may see improvements in symptoms such as abdominal pain, bloating, diarrhea, constipation and chronic fatigue when they avoid gluten-containing foods. However, avoiding gluten does not seem to help everyone manage these symptoms, so other changes in the diet may be recommended.

What About Food Sensitivity Blood Tests?

While "food sensitivity" is not an official diagnosis, the popularity of food sensitivity blood tests has grown. There are a variety of blood tests being offered that claim to test for food sensitivities, although there’s a lack of evidence to support their use.

Similar to allergy testing, these tests typically look for immunoglobulin antibodies:

• In the case of food allergies, skin pricks and blood tests that measure a protein called immunoglobulin E, or IgE, are used to diagnose the allergy. The presence of IgE antibodies generally indicates an immune system response.
• Food sensitivity tests typically look for the presence of IgG (not IgE). IgG antibodies have not been shown to reliably identify either food allergies or sensitivities. Most people produce IgG antibodies after eating food. They are not specific to a person's sensitivity, although past or frequent exposure to a food may cause these levels to be higher.

Because IgG blood tests have not been proven to identify food sensitivities or allergies, there is a lack of evidence to support making changes based on their findings. The restrictions suggested by IgG test results may lead to unnecessarily avoiding healthy foods. Or, they may prompt individuals with food allergies to include foods in their diet that could be harmful to them.

Professional organizations that specialize in the treatment of food allergies do not recommend IgG testing. This is why insurance companies will not cover the costs of the tests.

What To Do If You Suspect a Reaction to Food

If you think certain foods are causing health problems, what should you do?

• Make an appointment with your health care provider and explain your symptoms.
• Find out from your provider if you need a referral to an allergist for further testing.
• Ask your provider how you can learn about food allergies and food intolerances.

Based on your results, ask for a referral to a registered dietitian nutritionist. An RDN can design an eating plan for you based on your diagnosis, health needs and food preferences.