Food intolerance or sensitivity tests are becoming more available to the general population through recommendations from bloggers and naturopaths claiming that these tests can help with a wide variety of unresolved health issues. These IgG tests look at how much of this antibody is bound to each food and the respective removal of foods with high levels of IgG is said to improve symptoms. They are marketed by health and wellness influencers, as well as celebrities, who have sworn that their lives have been changed because of these tests. However, scientists and allergists say otherwise.

Food allergies vs intolerances

To delve deeper into the issue, it’s important to differentiate food allergies and food intolerances. Food allergies initiate immune responses that produce immunoglobulin E (IgE), which triggers the typical symptoms of an allergic reaction: itchiness and tightness in the throat, mouth, and airways. It can even be life-threatening if an anaphylaxis shock occurs. This can be alleviated by injecting epinephrine (think: epi-pen). Food intolerances or sensitivities, on the other hand, trigger a reaction by the digestive system, not the immune system. The American Academy of Allergy Asthma and Immunology (AAAAI) describes sensitivities to be “when a person has difficulty digesting a particular food.” Symptoms are usually stomach-related, such as bloating, abdominal pain, and diarrhea, but others have also reported headaches and fatigue as well.

If food intolerances are not an immune response, then why are these tests looking for IgG, which is part of the immune system?

Robert Hamilton, a professor of medicine at Johns Hopkins University who runs a diagnostic allergy laboratory said, “There is no firm, peer reviewed data that verifies that IgG antibody is diagnostically useful. This type of food insensitivity test is essentially a bogus test.” In fact, the presence of IgG antibodies for certain foods is actually to be expected, since we produce IgG antibodies to foods that we eat regularly. The AAAAI reports, “the presence of IgG is likely a normal response of the immune system to exposure of food… higher levels of IgG4 to foods may simply be associated with tolerance to those foods.” To confirm that, a study published in the Journal of Allergy of Clinical Immunology was published in 2010 even showed that IgG may actually be a marker for food tolerance. So don’t be alarmed when a bunch of your favorite foods pop up in your IgG test results.

“It doesn’t mean that you are sensitive or intolerant to those,” Hamilton says. “And it certainly doesn’t mean you should avoid exposure to them, or avoid eating them. This type of test is basically totally inappropriate. And how it can get on the market, and be sold, with these claims, is very disturbing.”

Despite this, food intolerance tests are doing very well in the market. In fact, EverlyWell, a home health testing company, received $6 million in sales 2017 and even received a one-million dollar investment from Shark Tank.

The general consensus in the scientific community

There is really no credible science backing up these food intolerance tests. The AAAAI emphasized, IgG and IgG subclass antibody tests for food allergy do not have clinical relevance, are not validated, lack sufficient quality control, and should not be performed…” and have “recommended against using IgG testing to diagnose food allergies or food intolerances/sensitivities.” Also, because these tests are laboratory-developed tests, they are not regulated by the Food and Drug Administration.

But ‘what’s the worst that can happen?’

Doing these tests can actually be harmful. Included in the fine print of these tests is usually a disclaimer that the report provided should be a ‘guide’ for elimination and is not a definitive diagnosis. However, the problem is these reports could encourage an individual to cut out certain food groups, which may cause malnutrition. Not only that, it may even trigger eating disorders by obsessing over what we can or cannot eat.

That being said, food intolerances are very real. It’s just that identifying these sensitivities cannot be done with just one test. While it is understandable that you want to look for alternative, non-medicinal ways to be healthier and to treat unresolved health issues, just keep in mind that these tests are not completely accurate, and that an old-fashioned elimination diet, albeit a huge hassle, would be a better bet in helping you feel better.