Should you take a microbiome test? 🧠

Here's what 69 global experts now say

Gut health tests are booming, but are they actually useful?

A new global report sets the record straight.

Tempted to order a gut test online, the kind that claims to reveal how “healthy” your microbiome is, diagnose gut issues, or tell you exactly what to eat (and which supplement to take)?

You’re not alone.

Thousands of people are sending off poo samples every week, hoping for answers to bloating, brain fog, or energy crashes.

But a first-of-its-kind consensus on microbiome testing from 69 international experts clearly sorts the science from marketing fluff.

What we’ll cover today:

• What microbiome tests are and how they work

• Common claims, and whether they hold up

• Can your gut be graded? What test results really mean

• Who microbiome tests might be useful for (and who they’re not)

• The expert consensus: the final verdict on gut microbiome testing

What is a microbiome test?

A gut microbiome test is an at-home kit that helps you understand the types and amounts of microbes living in your gut.

You collect a pea-sized scoop of poo into the kit’s container, then send it off to a lab in the post.

There, they analyse your sample.

A few weeks later, you get a report back, often with colourful charts, scores, and sometimes even food or supplement suggestions (we’ll come back to those).

Are at-home microbiome tests reliable?

There are different types of microbiome tests, and some are better than others.

Cheaper tests (like PCR) only check for a few bacteria, not enough to count as true microbiome tests.

16S sequencing is able to identify which bacteria are there, but only to a certain level.

Metagenomic sequencing is more advanced. It captures bacteria to a detailed level, and can suggest what the bacteria might be doing, like breaking down fibre. It’s also the most expensive.

Can your gut be graded? What test results really mean

Many reports use traffic lights, gut “types,” or diversity scores. But there’s no standard definition of what a “healthy” microbiome actually is.

Everyone’s gut microbiome is unique, as individual to them as a fingerprint.

So what’s “normal” for one person can look very different from someone else, even if they’re both healthy.

So while the reports might look impressive, a single test can’t tell you much, and it definitely can’t grade your gut as “good” or “bad”.

Your gut is a complex, personal system, and it’s not something that can be summed up with a simple score.

Common claims, and whether they hold up

Here’s what the 69 microbiome experts said about some of the most common claims on test reports and company websites:

“We can tell you how healthy your gut is.”
→ Not backed by science.
There’s no agreed definition of a “healthy” microbiome. What’s normal varies massively between people. Any test offering you a score or a pass/fail grade is overselling it.

“You have dysbiosis.”
→ Misleading.
This term gets thrown around a lot, but the experts were clear that it’s too vague to be clinically useful. They recommend it shouldn’t appear in test reports at all.

“Your results tell you exactly what to eat.”
→ Not backed by science.
Right now, the science simply isn’t strong or consistent enough to personalise diet advice based on your gut microbiome. Instead, general gut health advice still applies (and you don’t need a test for it).

“Your gut is imbalanced or not diverse enough.”
→ Framing matters.
While we often hear that more diversity is better, there’s no defined target for what a “balanced” or “diverse” microbiome should look like in a healthy person. Using these scores in reports can be more confusing than helpful.

“We compare your gut to a healthy reference.”
→ Often not true.
Many companies compare your results to their own customer database, not a validated, healthy control group. The report recommends using matched peer-reviewed reference populations, but most tests don’t.

“A single test is enough to understand your gut.”
→ Not really.
Your microbiome shifts all the time, depending on what you ate, how you slept, stress levels, and more (and even where you scooped from in the same poo). One sample is just a snapshot, and usually not enough to draw useful conclusions.

“This supplement or probiotic will fix your gut.”
→ Sales, not science.
The panel strongly advises against companies recommending products based on your test results, especially if they’re selling the products themselves.

“Microbiome tests can diagnose or screen for gut health issues.”
→ Not proven.
There’s currently no strong evidence that microbiome tests can be used to diagnose or screen for gut issues, mental health conditions, or chronic diseases. The science isn’t there yet, and using tests this way risks overpromising and underdelivering.

So… should you take a microbiome test?

For most people, the answer is no.

The expert panel is clear, microbiome tests aren’t currently useful for assessing your health.

They can’t diagnose gut problems, tell you what to eat, or guide treatment, even if you bring them to a doctor or nutritionist.

There are rare exceptions, like serious C. difficile infections, where testing can help guide treatment such as faecal microbiota transplants.

Microbiome tests are also valuable in research, helping scientists explore how gut microbes influence health and disease, like in my academic work at King’s College London. For transparency, I previously worked at an at-home microbiome testing company, mainly on the research side and briefly on the commercial side, before returning to academia.

It’s not the testing itself that’s the problem. The trouble is, the science just isn’t ready to tell us what the results actually mean for our health.

So what now?

One day, microbiome testing might help us personalise treatment, predict disease risk, or track recovery.

But we’re not there yet.

If you're struggling with gut symptoms, skip the test and speak to a healthcare professional instead, like a doctor or registered dietitian.

Two or three private sessions with a private dietitian often costs the same as a microbiome test (gut microbiome tests aren’t cheap), and save you some confusion too.

You don’t need a test to feed your gut microbes well

Focus on what we know works:

• Eat more fibre, like the BGBGs

• Add in fermented foods like yoghurt, kefir, kimchi, or sauerkraut

• Prioritise sleep, stress, and movement

These simple shifts have a far bigger impact on your gut health than any advice from a test kit can.

What do you think, is there value in knowing your gut bacteria, even if the science isn’t there yet?

Let me know in the comments below.

And chat soon,

Emily xx

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