Which gut tests are actually worth it?
This page states its position rather than hedging, and it publishes the cutoffs used to read each result. Reference ranges vary between laboratories, so read yours against the range printed on your own report.
The five worth doing
| Test | Type | What it separates |
|---|---|---|
| Faecal calprotectin | Stool | Inflammatory bowel disease from functional bloating |
| Coeliac (tTG-IgA) | Blood | Autoimmune gluten disease from wheat sensitivity |
| H. pylori | Breath or stool | A curable stomach infection from functional dyspepsia |
| SIBO / IMO breath test | Breath | Fermentation-driven from transit-driven bloating |
| Faecal elastase | Stool | Pancreatic enzyme insufficiency from food intolerance |
Faecal calprotectin
A stool marker of inflammation in the gut wall. It is the test that separates inflammatory bowel disease, meaning Crohn's disease and ulcerative colitis, from functional bloating and IBS.
Typical reading: under about 50 µg/g is normal, over roughly 150 µg/g is treated as raised, and the space between is a grey zone often repeated rather than acted on. A normal result is genuinely reassuring and means chasing food patterns is a sensible next move. A raised result needs a clinician, not a diet change.
It is cheap, widely available and high yield. If you are only going to do one stool test, this is usually it.
Coeliac serology (tTG-IgA)
A blood test for the autoimmune response to gluten. Coeliac disease is common, frequently missed for years, and entirely manageable once identified, which makes it worth excluding early.
A positive result usually leads to confirmation by endoscopy. It also settles the question permanently: gluten is a confirmed driver, and no amount of self-experimentation is needed to rediscover that.
H. pylori
A breath or stool antigen test for the stomach bacterium behind many ulcers and a good deal of upper-abdominal discomfort. Worth excluding if your main complaints are upper-tummy pain, reflux or early fullness rather than lower-abdominal bloating.
It matters because it is curable with a course of antibiotics. Treating it is the priority, and it is worth doing before spending months investigating food.
SIBO / IMO breath test
Measures hydrogen and methane in your breath after a sugar challenge, looking for bacterial overgrowth in the small intestine or excess methane-producing organisms.
The interesting part is that the two abnormal results mean genuinely different things:
- Hydrogen positive fits fermentation-driven bloating. Fermentable carbohydrates and meal timing are the levers.
- Methane positive (IMO) fits slow transit and constipation-type bloating. Symptoms are less tightly locked to individual meals, and more fibre often makes it worse rather than better, which is the opposite of the standard advice.
There is a lot more to say about this one, including the preparation errors that produce false positives and why recurrence after treatment is so common. We wrote it up separately in SIBO and methane overgrowth, explained honestly.
This test is more debated among specialists than the others here, particularly around standardisation and how often it produces false positives. It is on this list because an abnormal result meaningfully changes the model of what is happening, not because it is definitive.
Faecal elastase
Screens for exocrine pancreatic insufficiency, where the pancreas under-produces digestive enzymes. Worth considering if you get greasy, floating stools or diarrhoea after fatty meals.
Note that the direction is inverted compared with calprotectin: low is the abnormal result. Above roughly 200 µg/g is normal and below about 100 µg/g suggests insufficiency.
The reason this one matters disproportionately: the fix is prescribed enzyme replacement, not elimination. Someone with undiagnosed pancreatic insufficiency can spend years removing foods when the actual answer is a prescription.
The two that are not worth it
IgG food sensitivity panels
Verdict: not supported. Major allergy and gastroenterology societies advise against them.
The reason is mechanistic rather than a matter of quality. IgG antibodies to a food generally reflect exposure to that food, not intolerance of it. A panel showing high IgG to eggs, wheat and dairy in someone who eats eggs, wheat and dairy is largely reporting their diet back to them. Acting on it typically means removing a long list of foods that were never a problem.
Where it genuinely helps: essentially nowhere for bloating. IgE testing, which is a different antibody entirely, is a real and useful test for true allergy. Do not confuse the two. The full breakdown, with the society positions, is here.
Consumer microbiome and dysbiosis panels
Verdict: interesting, not actionable.
The underlying science is real and the field is moving. The problem is the gap between that research and a consumer report telling you your diversity is in the 34th percentile. There is no validated "healthy" reference microbiome, results vary substantially between labs and between samples from the same person, and crucially the report does not tell you which food to change.
Where they genuinely help: satisfying curiosity, and contributing to research if you consent to that. Neither is a diagnosis, and neither justifies the price if you bought it to find your triggers.
These panels also tend to be the ones with generous affiliate programmes, which is worth knowing when you read a review that recommends one enthusiastically. The full review, including the reproducibility data, is here.
What a result actually changes
A test is only worth doing if the result changes something. Here is what each one changes in practice, which is also exactly how Minthe uses them if you enter your results:
| Result | What it changes |
|---|---|
| Calprotectin raised | Stop chasing food patterns. This needs clinical assessment first |
| Coeliac positive | Gluten is settled. No self-testing required, and a strict gluten-free diet is the treatment |
| H. pylori positive | Treat the infection before investigating diet |
| Hydrogen positive | Focus on fermentable carbohydrates and meal timing |
| Methane positive | Focus on transit and stool patterns. Expect added fibre to feel worse |
| Elastase low | High-fat meals are the lever, and prescribed enzymes are usually the fix |
| IgG panel positive | Nothing. It should not drive a single dietary decision |
A sensible order
-
Rule out the serious and the curable
Calprotectin and coeliac serology first, plus H. pylori if your symptoms are upper-abdominal. These separate disease from functional bloating, and two of the three are directly treatable.
-
Explain the mechanism, if the first round is clear
A breath test if you are constipation-predominant or persistently bloated. Elastase if fatty meals reliably cause greasy stools or diarrhoea.
-
Then test yourself, properly
Once disease is excluded, the remaining question is which foods and daily factors actually drive your symptoms. No panel answers that. It takes repeated exposures compared against your own baseline, which is what the method behind Minthe is built to do.
On money, since it is relevant
There are no affiliate links on this page and we earn nothing from any test named on it. If that ever changes it will be disclosed at the top, and it will never extend to a test rated here as not worth doing. A page that rates tests honestly is worth considerably more than the commission on the ones that convert best, which are, predictably, the two at the bottom of this page.
Minthe is a wellness and self-tracking tool, not a medical device. It does not diagnose or treat any condition and isn't a substitute for professional medical advice. If you have red-flag symptoms such as blood in your stool, unintentional weight loss, difficulty swallowing, persistent vomiting or a fever alongside gut symptoms, see a clinician rather than tracking them.
Frequently asked
Which single test should I ask about first?
For most people with bloating plus diarrhoea or pain, faecal calprotectin and coeliac serology are the two highest-yield first steps, because they separate inflammatory and autoimmune disease from functional bloating. Both are inexpensive, widely available and change what happens next. Which is right for you depends on your symptoms, so ask your doctor rather than ordering blind.
Are IgG food sensitivity tests accurate?
No. Major allergy and gastroenterology societies advise against them. IgG antibodies to a food generally indicate exposure to that food rather than intolerance of it, so the panel largely reports what you have been eating. Acting on one usually means removing foods you tolerate perfectly well. Your own repeated with-and-without testing is stronger evidence than the panel.
Are consumer microbiome tests worth the money?
Not for working out what causes your bloating. They are scientifically interesting and the underlying research is real, but a dysbiosis score or a diversity percentile is not clinically validated for diagnosis and does not tell you which food to change. If you want the answer to what triggers your symptoms, structured self-testing gets you there and a microbiome panel does not.
Why does a methane-positive result change the advice?
Because methane tracks with slow transit and constipation rather than with meal-by-meal fermentation. If your breath test is methane positive, more fibre often makes things worse rather than better, and your symptoms tend to be less tightly locked to individual meals. That is a different model of what is going on, and it changes which patterns are worth looking for.
Do I need to be eating gluten before a coeliac test?
Yes, and this is the single most common way people lose the chance of a clear answer. Coeliac serology looks for the antibody response to gluten, so removing gluten beforehand can produce a falsely negative result. If you suspect coeliac disease, get tested before you change your diet, not after.
Do you earn commission on any test?
No. There are no affiliate links anywhere on this page. If that ever changes, it will be disclosed at the top of the page, and it will never apply to a test rated here as not worth it. Rating tests honestly is the entire point of this page.