Food Sensitivity Tests Are Popular, but Do They Work?

The science behind food sensitivity tests sounds legit—until you dig a little deeper.

You may have noticed an increase in ads and commercials for food sensitivity tests. These companies promise to offer life-changing answers to your digestive woes. In the commercials, a young woman often gasps upon learning she’s “sensitive” to dairy or a certain type of nut. As a result, she now knows to avoid this type of food, and can go on living a life without tummy troubles.

Notably, the commercials almost always feature women. That’s not surprising considering that women are more likely to experience gastrointestinal problems than men. Could food sensitivity tests really be the answer?

What Is Food Sensitivity?

It’s important to know that “food sensitivity” is not an actual diagnosis. It’s not the same as an intolerance or an allergy.

A food allergy is when your immune system perceives certain proteins in food as a threat. This launches an immune response. It creates antibodies (known as immunoglobulin E, or IgE) to defend the body against the food. This can lead to symptoms like:

  • Rashes and hives
  • Stomach cramps and vomiting
  • Shortness of breath and wheezing
  • Tight throat
  • Tongue swelling
  • Anaphylaxis, which can be life-threatening

A blood test by an allergist checks for levels of IgE antibodies after they expose you to a food allergen. When someone has high levels of IgE in their blood, it may mean they are overreacting to a certain food. In other words, they may have a food allergy. (This is not the same as a food sensitivity test.)

A food intolerance refers to having trouble digesting food, and it’s unrelated to the immune system. Lactose intolerance is the most infamous example. People with a food intolerance may lack a particular enzyme that helps to digest a specific food. As a result, they may have digestive symptoms (like cramps, gas, and diarrhea) when they eat too much of this food.

Food sensitivity is a vague term with no official definition. This may lead you to ask: What exactly are these tests measuring?

The Problem with Food Sensitivity Tests

Food sensitivity tests claim to measure your body’s “immune response” to different foods. However, they’re not measuring your IgE levels, which is the antibody associated with food allergies. Instead, the tests work by measuring your immunoglobulin G (IgG) antibody levels.

IgG antibodies usually respond to bacterial and viral infections.They do not appear to reliably predict negative reactions to food, according to the Academy of Nutrition and Dietetics. In fact, producing IgG antibodies is a normal process after a meal. Having IgG antibodies for a particular food may mean that you’ve had exposure to the food (via eating it), and not that you have any sort of harmful reaction to it.

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Should You Try It?

Food sensitivity tests are not cheap. If you’re going to spend a couple hundred dollars on something, you want to make sure it’s a valid and reliable product. Due to the weak relationship between IgG antibodies and diet, it may be better to go a different route to get answers.

If you don’t currently have any digestion issues, taking a food sensitivity test may do you more harm than good. It may motivate you to cut out certain foods from your diet that actually weren’t causing you problems. This may lead to a restricted diet that deprives you of healthy or pleasurable foods for no valid reason.

On the other hand, if you’re suffering from digestive symptoms like gas, bloating, cramping, constipation, or diarrhea, your first step should be to see your doctor and/or a registered dietitian. You may have a food intolerance or perhaps a medical condition like irritable bowel syndrome. If necessary, you could try an elimination diet under the guidance of a registered dietitian to pinpoint which foods are giving you trouble.

It’s enticing to be able to learn about your body with a simple blood test, but talking to your doctor is a better investment. Until there’s an officially recognized definition of “food sensitivities,” and until tests have reliable ways of measuring them, you might want to save your money.