Broad panels, IgG testing unnecessary for food intolerances, sensitivities

Key takeaways:

• Food allergies, intolerances and insensitivities are different.
• The presence of food-specific IgG has yet to be proven a bad thing.
• When tests claim to be supported by research, that research should be examined.

Editor’s Note: In Healio Allergy/Asthma’s column, “Food Allergy: Fact vs. Fiction,” Douglas H. Jones, MD, breaks down what’s true and what’s myth for a variety of topics related to food allergies. If you have a question you would like answered in this column, email Jones at rmaaimd@gmail.com or Richard Gawel at rgawel@healio.com.

If you are a pediatrician, family practice doctor, naturopath or chiropractor, I beg you to stop ordering broad food allergy panels and food IgG tests. Please.

Many patients get their “education” online from social media, whether it is credible or not. As I watch many patients promote their pages, many of them proclaim that they have severe food allergies and often advertise how they live with 20 or more, 30 or more or possibly even 40 or more food allergies.

Douglas H. Jones

I have contacted a few of them to help them since I have treated thousands of patients with food allergies. Among the few who have responded, I have discovered an interesting thing: They do not have that many true allergies.

They may have a variety of adverse reactions to foods, but after taking a careful history, it is clear that not all of these reactions are allergic.

However, these patients say they have had “broad panels of food allergy and food sensitivity testing.” Their doctors have fallen prey to the marketing from the companies making money from these tests and have ordered them.

The reality with these patients (and many others) is that they have a mix of several different kinds of adverse reactions to foods, but not all of them are allergies. Some patients have just one type and others have another type.

Why does this matter? Let me use an analogy. What if every patient who had dyslexia or ADHD was lumped into the autism spectrum? How effective would the treatment plans be?

That would be very similar to labeling food intolerances or sensitivities as food allergies. They are not the same. The risks are not the same. Testing is not the same. Interpretations of tests are not the same. Treatment and approaches, certainly, are not the same.

But the ramifications on someone’s life can be massive and often detrimental when we are not right or specific. It is important that patients avoid foods that they absolutely need to avoid, but unnecessarily avoiding foods can be detrimental on many levels.

It is critical we get it right. If you do not know what you do not know or are unfamiliar with the nuances of various adverse reactions to foods, then it is credible and admirable to refer patients to those who do. Please, do not test prior to doing that, just refer your patients.

Let us dive into this and clarify the controversy and myths a bit more. What are the critical differences between food allergies, food sensitivities and food intolerances? Hundreds of articles define these terms, but I want to give you a simple way to think about them.

Of note, there are more ways than these three that food can affect the body, such as celiac disease, small intestinal bacterial overgrowth or food protein induced enterocolitis. But for our purposes, I will address these three broad categories.

Food allergies

True food allergy is an immune-mediated response that usually occurs quickly, is reproducible and can occur with any amount of exposure to foods. When the immune system is activated, it signals a cascade of events mediated primarily through an antibody called IgE.

The subsequent release of many chemicals including histamine, tryptase and other inflammatory proteins and cells yield classic allergy symptoms that can affect multiple systems, including the gastrointestinal (GI) tract, respiratory tract, cardiovascular system and skin. This can potentially be life-threatening, and extreme caution needs to be exercised with strict food avoidance.

We can detect food-specific IgE in the blood or in a skin test. This provides some evidence of what food allergies one may have. However, these tests are not perfect and not completely diagnostic. There can be false positives and false negatives.

Tests must be interpreted by someone who understands their nuances and who can explain the results in the context of that patient. All too often, these tests are done, and patients are told to unnecessarily avoid foods they may not truly be allergic to, creating a tremendous burden.

The lesson goes back to medical school 101. If you don’t know what you don’t know and can’t interpret a test, don’t order it in the first place. Rather, refer to someone who can. Some newer emerging tests such as basophil activation tests can be done in select centers in the United States.

Food intolerances

Food intolerances involve enzyme deficiencies, the nervous system and exogenous histamine. Symptoms are located within the GI tract such as nausea, vomiting, bloating, gas and diarrhea. Most likely, they are dose-related. They also are not life-threatening, but they may make the patient feel, well, crappy.

Food sensitivity

This is where foods may cause gut inflammation. These patients often will come in with abdominal pain or vague constitutional symptoms and say that they want a broad panel of tests done to find their hidden or unknown food allergies.

Symptoms can be immediate or delayed, occurring hours to days after the food was ingested. Primarily, like food intolerances, symptoms are in the GI tract and they may even cause gut inflammation (not mediated through IgE) that leads to the common symptoms of gas, bloating, diarrhea, constipation, brain fog, joint pain or fatigue.

These symptoms can be inconsistent with eating and inconsistent with the same foods. It is difficult because symptoms also may be delayed or chronic. This is a very common occurrence, and these patients are desperately seeking answers.

To address this need, there was a concept developed years ago that perhaps patients were experiencing a different kind of immune response to the food by other antibodies besides IgE. Food-specific IgG was evaluated, and it was found that people indeed do make food-specific antibodies – specifically IgG. It was postulated that this is what accounted for the food sensitivities, or “delayed food allergy.”

Makes sense, right? People are having food issues. They may not be making IgE, but they are making IgG, which is part of an immune response. That, therefore, is the missing piece!

Except, it isn’t.

But this is the hope that companies that make these tests sell so creatively to patients desperately seeking it.

Many companies and doctors who sell these tests claim these reactions occur because the body produces the IgG antibody, which may not trigger the immediate allergic reaction but rather a more delayed reaction for “hidden” or “low-level” food allergies, sensitivities or intolerances.

There is usually a spin that conventional doctors do not check this test, implying that the doctors promoting these tests know better. So, they focus the marketing on how a food-specific immune response is taking place.

However, this omits or ignores how not all immune responses are necessarily bad. We need an immune response to develop tolerance and insensitivity. The presence of food-specific IgG has yet to be proven a bad thing. I have not seen a study validating this test or showing reproducibility that correlates clinically with the patient’s history.

In fact, IgG to food exists in the body under normal conditions and is likely more of a measure of what is in the diet. Further, when allergists treat legitimate food allergies with oral or sublingual immunotherapy, IgG to those foods will increase and demonstrate tolerance, not intolerance or sensitivity. I have yet to see valid studies showing that IgG causes the negative inflammation that is claimed.

Even more problematic is how the references that these doctors cite often are from magazine articles, “their own research,” unreputable journals or animal studies or are sorely out of date. Why do they do this? Because most people may look to see if there are references, but they will not look beyond at the actual reference. They will trust the phrase, “Research shows ...”

Here are some take-home questions to ask ourselves when we see the phrase, “Research shows ...”

• Was the research in humans or just animals?
• How many studies were conducted?
• Were the studies legitimate and validated?
• What were the research methods?
• Were there conflicts of interest?
• Who funded the study?
• Does the research show what these doctors are claiming?
• Have the results been reproduced?
• Does the “reputable doctor” advertising the test benefit from others ordering it?
• If there is something “specially formulated” that nobody else knows about, why does nobody else know about it?
• What do other experts in the field think of the studies, tests or treatment?

Douglas H. Jones, MD, FAAAAI, FACAAI, is cofounder of Global Food Therapy, Food Allergy Support Team and OITConnect, the director at Rocky Mountain Allergy at Tanner Clinic, and a Healio Allergy/Asthma Peer Perspective Board Member. He can be reached at rmaaimd@gmail.com or on Instagram @drdouglasjones.