Consumer microbiome tests
Also called: gut health test, microbiome testing, stool test kit.
Last reviewed 2026-09-16. How this works.
Guiding treatment Grade D
No human evidence of benefit, or none that survived testing.
Send the same sample to two of these companies and you can get two opposite answers back.
Same sample, two companies, opposite verdicts. No approved clinical test exists.
The claim
The claim is that a home gut microbiome test can tell you something useful about your health, and by extension about your cancer or your treatment.
What it does
The microbiome does influence how some cancer treatments work, which is why the rest of this chapter exists. This entry is about whether a consumer test can measure it reliably enough to act on, which is a different question.
The evidence
Seven consumer services were sent a standardised faecal material developed by a national standards institute. The variability between providers analysing identical material was on the same scale as the biological variability between different donors.1
Within companies it was no better. One provider issued a consumer report on a replicate in which more than half the reads were unidentified. Replicates of the same stool were in one case classified as both healthy and unhealthy, with different dietary advice attached to each.2
An international consensus statement records that evidence for the clinical usefulness of the gut microbiome as a diagnostic tool is scarce, that providers sell these tests without any consensus on their regulation or proven value, and that there are currently no regulatory-approved clinical microbiome diagnostic tests.3
The general lesson is the useful part, and it transfers to any test anyone is offered: does it measure what it claims, does that measurement relate to a real condition, and does knowing it change what anyone would do. This one fails at the first.13
The studies this rests on
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Analytical performance of seven direct-to-consumer gut microbiome testing services1
A laboratory study, not in people, measured a laboratory marker, not an outcome, 7 animals.
variability between providers on the same scale as biological variability between different donors.
What is absent
There is no regulatory-approved clinical microbiome diagnostic test. Nothing sold direct to consumers has been approved for guiding any treatment decision.
Scope: clinical microbiome diagnostics.
Established by published review, international consensus statement on microbiome testing in clinical practice, checked 2026-09-16. Result: no regulatory-approved clinical microbiome diagnostic tests currently exist.3
What to ask
Would a gut microbiome test result change anything about how you would treat me?
The dish-to-person gap
This is a test rather than a treatment, so no pharmacokinetic profile applies.
When to call your team — no warning signs are recorded
If this is something you are considering or have already had done, the people treating you can only weigh it if they know about it. That is true when nothing has been written down here, and it is most true then.
The register records no warning signs for this entry. The risk here is a decision made on an unreliable result rather than a physical harm.
Interactions
A test is not checked against treatment classes in this register.
The whole interaction list, and how to turn it into a pharmacy review request.
Find a trial instead
There is no approved clinical microbiome test to enrol in.
References
Evaluating the analytical performance of direct-to-consumer gut microbiome testing services. Communications Biology, 2026.
doi:10.1038/s42003-025-09301-3
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 23 note 21.
Reported findings from the study above as summarised in professional coverage.
No persistent identifier recorded.
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 23 note 22.
International consensus statement on microbiome testing in clinical practice.
How this was reached: transcribed from chapter note, via docs/CHAPTER-NOTES.json, chapter 23 note 23.