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Food sensitivity reports come in many forms — from lab tests to AI analysis of your food diary. Here's what the different types actually contain and how to read them.
13 March 2026
You've probably seen ads for food sensitivity tests. A blood draw or saliva sample, a few weeks of waiting, and then a report arrives — sometimes dozens of pages long, listing foods you're "sensitive" to with accompanying charts and severity ratings.
These reports look authoritative. They're often expensive. And they're frequently misleading.
I want to walk through the different types of food sensitivity reports that exist — what they contain, what the results actually mean, and how to read them without being misled.
This is the most common type of commercial food sensitivity test. Companies like YorkTest, Everlywell, and many others offer panels testing for IgG antibodies against 50–200+ foods.
IgG antibodies indicate exposure. When you eat a food regularly, your immune system produces IgG antibodies against proteins in that food. This is a normal immune response — not evidence of sensitivity or intolerance.
A "positive" result for wheat on an IgG test means you eat wheat regularly and your immune system has noticed. It does not mean wheat is causing your symptoms.
The major allergy and gastroenterology professional bodies — including the British Society for Allergy and Clinical Immunology (BSACI) and the American Academy of Allergy, Asthma & Immunology (AAAAI) — do not recommend IgG food sensitivity tests for diagnosing food intolerances. The science does not support using IgG levels to diagnose food sensitivity.
These reports typically show a bar chart or grid with each tested food and a result ranging from "normal" to "elevated" or similar. Foods are often colour-coded (green = fine, yellow = consider reducing, red = avoid). The visual presentation implies clinical precision that the underlying science doesn't support.
If you've already had one of these tests and gotten results, don't panic — but treat the results as a very rough starting hypothesis, not a diagnosis. Foods flagged as "high" are worth testing properly through elimination and reintroduction, but only because they're worth investigating, not because the IgG result means anything diagnostic.
This is medically validated and used by allergists. It tests for IgE antibodies — the immune response involved in true food allergies.
Skin prick tests or specific IgE blood tests (RAST tests) identify which food proteins your immune system has developed a rapid allergic response to. A positive result means there's a risk of an allergic reaction to that food.
A positive IgE test doesn't guarantee a clinical reaction — some people have detectable IgE antibodies to foods they eat regularly with no problem. Allergy diagnosis requires correlating test results with clinical history, typically assessed by an allergist. Never use home IgE tests to self-diagnose food allergies.
These come from labs or allergy clinics and show specific IgE levels in kU/L (kilounits per litre) for each tested food, along with reference ranges. The numbers require clinical interpretation alongside your symptom history.
Hydrogen breath tests are the validated clinical tool for diagnosing lactose intolerance, fructose malabsorption, and small intestinal bacterial overgrowth (SIBO).
You consume a test substance (lactose, fructose, or lactulose), and hydrogen levels in your breath are measured at intervals over 2–3 hours. Elevated hydrogen indicates fermentation in the gut — meaning the substance is reaching the large intestine unabsorbed (lactose/fructose) or there are bacteria fermenting in the small intestine (SIBO).
A graph showing breath hydrogen levels over time, with baseline and peak readings. Results are interpreted as positive or negative based on how much hydrogen is produced and when the peak occurs.
This test is actually meaningful — it directly measures a physiological process rather than an immune marker.
This is the type I find most practically useful for IBS — not because it looks most authoritative, but because it's based on your actual response to specific foods rather than a proxy marker.
A report generated from 4–6 weeks of tracking data typically contains:
This type of report is typically generated by AI analysis of your tracking data, combined with structured elimination testing results over the following months.
Regardless of the type of report you're looking at, ask these questions:
The validated diagnostic pathway for food intolerances is:
This is less exciting than a detailed report with colour-coded charts. It takes longer. It doesn't produce a single impressive document you can point to. But it's the approach that actually identifies whether specific foods cause symptoms in your specific body.
If you've spent money on an IgG test and received a report, use it as a starting hypothesis for elimination testing, not as a final answer. Test the foods flagged as "high" using proper elimination and reintroduction. You may find some are genuine triggers (confirmed through elimination testing) and others aren't.
The IBS & Food Sensitivity Tracker makes logging simple — then uses AI to find patterns you'd miss on your own.
Get the Tracker →Commercial IgG food sensitivity reports look authoritative but measure immune exposure, not food sensitivity. Allergy (IgE) testing and hydrogen breath tests are clinically validated for their specific purposes. The most reliable "report" for IBS food triggers comes from systematic elimination testing documented through careful tracking — less impressive looking, but far more accurate.
A simple, low-pressure way to start noticing patterns between what you eat, how your gut feels, and what might actually be triggering symptoms - before you commit to the full tracker.
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