For a few hundred dollars you can put your poo in an envelope and post it off to a laboratory. In return you’ll get a report (sometimes generated by AI) outlining your food sensitivities, metabolic fitness, and what pathogens or fungi you’re harbouring.

These at-home gut microbiome tests or “GI mapping” kits are frequently promoted by influencers as a way to “hack your health” and “take control” through analysing some of the trillions of organisms that live in your digestive tract.

But how much can an at-home gut test really tell you, and are they actually worth doing?

Even experts struggle to interpret at-home microbiome tests

Prof Rupert Leong, a gastroenterologist and microbiome researcher based at Macquarie university hospital, is increasingly seeing patients alarmed by gut microbiome reports they don’t understand.

Leong said depending on what is being analysed, gut microbiome testing can be “very powerful and accurate” in detecting microbial markers. But interpreting what those markers mean for an individual remains a major challenge, and different labs vary in their methodology, leading to differing results.

“We are still in the infancy of understanding how to interpret them,” he said.

If a gut microbiome test is ordered by a specialist doctor or accredited dietitian with a clear clinical reason, sent to a reputable lab, and interpreted by someone trained to make sense of the results, it can be genuinely helpful.

Leong recently saw a patient with inflammatory bowel disease and rectal bleeding who had already undergone standard medical tests. The microbiome results, in that case, helped confirm dietary issues and guide further treatment once simple and important issues had been ruled out.

But these cases are the exception, he said.

A healthy mix of organisms in one person could be problematic in another; “The same organism has different species and acts differently in different individuals,” Leong said.

It means for the vast majority of people who order these tests online, and who may be curious about their gut health or wondering about their symptoms or foods to avoid, “there are no translatable benefits” to ordering a test, he said.

Temporary dietary changes, medications or illness could all affect the results, and what those results actually mean for an individual’s health outcomes isn’t well understood.

False alarms can cause distress

One of Leong’s patients who took a commercial home test came to him panicking about bowel cancer after the report suggested she had certain inflammatory markers.

Leong said a colonoscopy remains the definitive test to investigate bowel polyps and cancers. The free home bowel screening test issued by the Australian government, which looks for hidden blood in stool, is an evidence-based way to detect early warning signs of bowel cancer and may prompt follow-up testing, including a colonoscopy.

And while some home gut microbiome tests claim to offer insights into metabolism or inflammation, “very few experts can use these results appropriately at present,” Leong said, including gastroenterologists.

This is because clinicians aren’t trained to interpret the complex outputs the tests generate, the science is still developing, and there aren’t clear guidelines on what to do with the information.

The illusion of control

At-home microbiome tests are spruiked by online influencers as a way of empowering people who want more insights into their health. But Dr Erica Zurawski, an assistant professor in environmental studies, said this encourages consumers to internalise health responsibility while giving their personal data to large for-profit companies.

Her research has examined how direct‑to‑consumer microbiomeare often pitched “as a wholesale solution to myriad health issues when, in fact, they oversimplify the complexity of the inner workings of the gut, its malleability, and the impact external factors have on it,” she said.

It makes people feel they are doing something wrong, “while the underlying issues that cause poor gut health,” including the influence of harmful industries and government policies, are “side-stepped,” she said.

“This complexity gets smoothed over and ignored … testing kits fail to account for things such as stress, pollution, or access to meaningful health care to address adjacent health issues.”

Back to basics

So how can you actually support gut health?

Leong says: “A diverse diet, high in fibre” is a sensible place to start.

Zurawski adds that governments have a responsibility to address the broader social and environmental conditions that influence gut health, including poverty, housing, pollution, and access to affordable, nutritious food.

If you are experiencing gut symptoms or concerns, Leong recommends seeing a qualified dietitian or GP before jumping to expensive, at-home testing.

Melissa Davey is Guardian Australia’s medical editor

Antiviral is a fortnightly column that interrogates the evidence behind the health headlines and factchecks popular wellness claims