TL;DR — Bottom Line
- IgG food panels are not recommended by major allergy organisations for diagnosing food sensitivity. IgG antibodies to food are a normal marker of exposure, not of intolerance.
- IgE testing is different and legitimate — it is for genuine allergy, ordered and interpreted clinically, not a consumer wellness product.
- Breath testing is the validated route for lactose and fructose malabsorption, which explains a large share of real food-related symptoms.
- A structured elimination and reintroduction protocol remains the reference method for identifying trigger foods, and it costs nothing but attention.
- The harm is not just the money. IgG panels routinely flag dozens of foods, and needlessly narrowed diets are a genuine nutritional and psychological risk.
Quick Picks
Food sensitivity testing is the largest category in consumer health testing where the science and the marketing diverge most sharply. The demand is entirely genuine — a great many people have real, reproducible food-related symptoms — and the most heavily marketed products are the ones with the least support behind them.
This guide is organised around a single distinction: tests that measure something causally related to symptoms, and tests that measure something normal and present it as a problem. Getting that distinction right saves money, and more importantly saves people from unnecessarily restricted diets.
Testing Approaches and Their Evidence
| Approach | What it measures | Evidence status | Appropriate use |
|---|---|---|---|
| IgG food panel | IgG antibodies to foods | Not recommended by allergy bodies | None established |
| IgE allergy test | IgE antibodies | Validated with clinical context | Suspected true allergy |
| Lactose breath test | Hydrogen from unabsorbed lactose | Validated | Suspected lactose intolerance |
| Fructose breath test | Hydrogen from unabsorbed fructose | Validated | Suspected fructose malabsorption |
| Coeliac serology | tTG-IgA antibodies | Validated | Suspected coeliac disease |
| Elimination and reintroduction | Symptom response | Reference method | Most food-related symptoms |
| Hair, IgG4 or bioresonance tests | Various | No supporting evidence | None |
Why IgG Panels Do Not Do What They Claim
IgG is an antibody class produced in response to exposure. Producing IgG antibodies to foods you eat regularly is a normal immunological finding — it indicates that your immune system has encountered the food, which it has, because you ate it.
Major allergy and immunology organisations across several countries have issued position statements advising against the use of IgG food panels for diagnosing food allergy or intolerance, on the grounds that the antibodies measured do not indicate a pathological response. Some evidence points in the opposite direction from the marketing entirely, with food-specific IgG in some contexts associated with tolerance rather than reaction.
This produces a predictable pattern: the panel flags the foods you eat most often, the report recommends eliminating them, and symptoms sometimes improve — because eliminating a large fraction of your diet usually removes whatever the actual trigger was, along with a great deal else. That is not the test working; that is an accidental and badly designed elimination diet, and it comes with real nutritional risk and a narrowed relationship with food that can be hard to reverse.
What Real Food-Related Conditions Look Like
Genuine food allergy is IgE-mediated, typically rapid in onset, and can be severe. It is diagnosed with skin prick or specific IgE testing interpreted alongside clinical history — test results alone frequently show sensitisation to foods a person tolerates perfectly well, which is exactly why clinical context is required rather than optional.
Coeliac disease is an autoimmune condition triggered by gluten, diagnosed through serology and usually confirmed by biopsy. Critically, testing must be performed while still eating gluten — removing it before testing produces false negatives and is one of the most common reasons a diagnosis gets missed for years.
Carbohydrate malabsorption — lactose being the most common — is measured by breath testing, using the same hydrogen-in-breath principle as SIBO testing. It is a real, measurable, common condition and it explains a substantial fraction of the symptoms people attribute to vaguer sensitivities.
Then there is the large remaining category of non-allergic food intolerance, including FODMAP sensitivity in irritable bowel syndrome. There is no blood test for it, and there does not need to be, because a structured elimination and reintroduction protocol identifies triggers directly.
How to Run an Elimination Protocol Properly
The reference method for identifying food triggers is unglamorous and effective. Establish a baseline by logging symptoms for two weeks without changing anything, then remove a defined group of suspect foods for two to six weeks, then reintroduce them one at a time with several days between each while continuing to log.
Two rules make the difference between a protocol and a mess. Reintroduce one food at a time, in a meaningful quantity, with enough spacing to attribute any reaction. And put a hard end date on the elimination phase — the purpose is to identify triggers so the diet can be widened again, not to establish a permanently restricted diet.
For a structured low-FODMAP protocol in particular, working with a dietitian materially improves both the accuracy of the result and the breadth of the final diet. It is the intervention with the best evidence in IBS, and it is also the one most often done badly when self-directed, ending in unnecessary long-term restriction.
Tests and Tools That Are Actually Useful
These are the products that measure something meaningful or support a protocol that does. Notably absent is the largest-selling category in this market, for the reasons above.
Lactose Intolerance Breath Test Kit
Measures hydrogen produced by bacterial fermentation of unabsorbed lactose — a direct measurement of malabsorption rather than an inference from antibodies. Lactose intolerance is common and frequently mistaken for a broader sensitivity.
Who it is for: anyone whose symptoms follow dairy, which is one of the most common real patterns.
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Shop Lactose Breath Test Kits on AmazonCoeliac Disease Screening Test
Measures tTG-IgA antibodies, the standard first-line screen for coeliac disease. Must be done while still eating gluten, and a positive result needs clinical follow-up rather than a self-directed diet change.
Who it is for: anyone considering removing gluten — test before eliminating, not after.
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Shop Coeliac Screening Tests on AmazonFructose Malabsorption Breath Test
The same validated breath-gas method applied to fructose. Fructose malabsorption overlaps heavily with IBS symptoms and with the effects of high-fructose sweeteners.
Who it is for: people reacting to fruit, honey, or products sweetened with high-fructose syrup.
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Shop Fructose Breath Tests on AmazonLow-FODMAP Elimination Diet Guide & Cookbook
The structured protocol with the strongest evidence base in IBS. A good guide covers the reintroduction phase properly, which is the part self-directed attempts usually skip.
Who it is for: anyone with IBS-pattern symptoms who wants the evidence-based approach rather than a blood panel.
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Shop Low-FODMAP Guides on AmazonSymptom & Food Tracking Journal
The only instrument an elimination protocol strictly requires. Timing between food and symptoms is what identifies triggers, and memory reconstructs that connection unreliably.
Who it is for: everyone running an elimination protocol, and anyone preparing for a clinical appointment.
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Shop Food and Symptom Journals on AmazonWhich One Fits Your Situation
The demand behind this market is legitimate. People have real symptoms, they are frequently dismissed, and a test promising specific answers is enormously appealing when nobody has offered any. That appeal is exactly what the IgG panel market runs on.
The genuinely useful path is less satisfying and more effective: rule out coeliac disease before removing gluten, breath-test for lactose and fructose if the pattern fits, run a properly structured elimination with reintroduction for everything else, and take a symptom log to a clinician. This is general information, not medical advice, and symptoms including unexplained weight loss, blood in stool, difficulty swallowing, or any rapid allergic reaction need clinical assessment rather than a home test.