What does your stool test say about your health?

Your stool test says more about you and your wellbeing than you might think, writes Dr Ken McGrath.

Stool tests. Something most of us are aware of, not many understand, and few want to talk about. Yet, stool tests in many cases are lifesaving, and some of the more modern tests can provide detailed insights into what is going on in an individual’s gut. So how do we understand the different types of tests, why they’re important, and exactly what they can show us?

Change in perception

Gut health is something of a “hot topic” over the last decade, with the community and scientists alike. This can be seen in the plethora of gut health articles in magazines, on television and on the internet.

Once upon a time, it was thought that the “only good bug is a dead bug”, but now we’re starting to understand the links between the gut and overall health. The gut microbiome – the community of bacteria living in an individual’s gut – has gone from the relatively unknown, to a word of possibilities.

What are the different tests available?

There are several common tests for gut-related concerns – some of which may be more well-known than others. The different kinds of stool tests either look at human-produced compounds, specific bacteria and parasites, or profile the whole microbiome living in the gastrointestinal tract to see what organisms are living there and what they are doing.

We see tests such as the National Bowel Cancer Screening Program and the test for irritable bowel disease searching for blood in stool or inflammation markers, whereas the tests that search for specific bacteria or parasites are detected through blood or microscope.

Exploratory tests to see what is living in the gut microbiome and what the bacteria is doing were previously done via cell culture – growing bacterial colonies on a plate – or 16S rRNA sequencing – looking at a small piece of the genome and predicting the species present.

The world-leading way to test the gut microbiome these days is through metagenomic sequencing, which analyses the DNA of all the organisms in a sample. This means that laboratories – such as Brisbane-based Microba – can look at all of DNA in the sample rather than previous methods, which sequenced less than 5 per cent.

What does this mean?

There are many tests out there that look at different aspects of your gut health by looking for different information. Tests such as the bowel cancer screening test and searching for parasites are important, and if you are sent one in the mail, or asked by your doctor to undertake these, you definitely should! But when it comes to exploring your own gut health to gain more understanding on what it’s doing and the bacteria living in there, metagenomic sequencing is the best method available.

Dr Ken McGrath is the technology liaison manager with Microba.