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A Common Scenario
Patient: Doctor, I just get stomach aches every time I eat. Is it a food allergy that I don’t know about? Can I get a panel of tests done?
Doctor: Well, let’s check it out. I will order a broad panel of food allergy tests to see.
This scenario must end. I hear it every day. Patients bring me broad panel test results—some validated, others not. Many times, neither the patient nor the ordering doctor know how to interpret them.
Often, these tests show mildly positive results to many foods the patient eats without symptoms. The usual advice is “avoid these foods for a few weeks, then slowly reintroduce.” Naturally, patients get frustrated—it doesn’t make sense, it’s difficult to follow, and they still don’t feel well.
So what’s really going on?
Food Allergy vs Other Food Reactions
The first thing to realize is that not every symptom after eating is “food allergy.”
Other possibilities include:
- Food sensitivities
- Food intolerances
- Celiac disease
- Gastroenteropathies
- Non-IgE mediated food allergy
It’s wrong to lump all of these into “food allergy.” That’s like saying every seizure or neuropathy is a stroke.
Five Key Questions About Food Allergy Testing
- What kind of validated food allergy tests are there?
- What do food allergy tests really mean?
- When should they be ordered?
- What should be ordered?
- What about food intolerances and food sensitivities?
Let’s break them down.
Validated Food Allergy Tests
The most common validated food allergy tests are:
- Skin prick testing (not intradermal, due to risk of systemic reaction)
- Serum IgE tests (including specific foods and component tests)
Investigational tests:
- Basophil activation tests
- Epitope testing
Non-validated tests (not supported by evidence, despite marketing claims):
- IgG testing
- Kinesiology or NAET testing
- Saliva analysis
- Hair analysis
- Electrodermal testing
- Flow cytometry for WBC morphology
What Do Food Allergy Tests Really Mean?
Do they show severity of an allergy? No
Do higher numbers mean a more severe reaction? No
Does a positive test confirm food allergy? No
Does a negative test rule it out? No
Here’s what they actually mean:
A positive test indicates the likelihood that someone may react upon exposure. That’s it.
Severity? Not shown.
Confirmation? Not on its own.
Food allergy diagnosis requires history first, test second. The tests only support the clinical picture.
When Should Tests Be Ordered?
Food allergy tests should only be considered when a patient has a history of symptoms consistent with food allergy.
- Isolated gastrointestinal symptoms are not typical of IgE-mediated food allergy.
- They are more consistent with food sensitivities, intolerances, or conditions like celiac disease.
- Non-IgE mediated food allergies (like FPIES) can cause GI symptoms with risk of severe reactions, but the history is key.
What Tests Should Be Ordered?
Tests should be specific and targeted, guided by patient history. Broad panels to “find the unknown allergy” are not appropriate.
If reactions are inconsistent or not reproducible, other diagnoses besides IgE-mediated food allergy should be considered.
Ordering broad panels often leads to misdiagnosis, unnecessary avoidance, and wasted time. Medical school 101 teaches: if you don’t know how to interpret a test, don’t order it. Refer to a specialist.
Food Intolerances and Sensitivity Testing
This is a topic for a future blog, but here’s the takeaway:
- Refer back to the non-validated test list above.
- Ask: “Why are these tests not validated?”
- Look at actual peer-reviewed data, not company marketing or paid experts.
Most of these tests have shown no correlation with real symptoms in clinical trials. So why order them? Just because a test exists doesn’t mean it should be used.
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