Leading gastroenterologists have warned against a new direct-to-consumer test that promises to reveal the good and bad bacteria in a person’s gut, despite high-profile endorsements of the technology.
Cervical cancer vaccine pioneer, Professor Ian Frazer, is director of the start-up company Microba, which is inviting Australians to pay $349 for metagenomic sequencing of their gut biome.
The mail-order faecal swab kit was launched in July at an event MC’d by renowned dietitian, Dr Joanna McMillan, who in February presented an episode of ABC TV’s Catalyst program on how DNA testing was “driving the gut revolution”.
Microba customers are promised personalised reports based on their test results, including data on their microbiome’s potential to digest carbohydrates, protein and fat, and to produce essential vitamins such as folate. They are also offered personalised dietary information.
Dr Alena Pribyl, Senior Scientist at Microba told doctorportal: “When you eat food, most of it is going to be processed by digestive enzymes in the stomach and absorbed in the small intestine, and then what can’t be digested – fibre and excess protein – passes to the large intestine where it’s available for microbes to digest. These microbes produce their own enzymes.”
She continued: “What our test can do is look at different genes in each of those microbes that can break down fibre and protein, and see what enzymes the bacteria can produce.”
Microba has stressed that its test is not diagnostic, but says on its website: “Once you have the clear picture of your gut, you can make changes to improve wellbeing.”
For instance, Dr Pribyl said if the test showed a low potential for the gut microbiome to produce butyrate people might respond by increasing their intake of fibre, in particular resistant starch.
Over-interpreting the results
However leading gastroenterologists say interpreting and responding to the test results is not straightforward, nor evidence-based. Many have criticised the move to offer testing direct-to-consumers.
Professor Peter Gibson at Monash University, whose discoveries about the low FODMAP Diet have transformed the management of irritable bowel syndrome, told doctorportal the technology offered exciting research possibilities but had no present clinical utility.
“This [test] has no use since we do not know what the results mean in terms of therapy, diet, etcetera… Acting upon the results is not evidence-based,” he said. “While we still debate what ‘dysbiosis’ is, what is cause and what is effect, and what it all means, these tests should not be used in clinical practice.”
He added: “The results are likely to be over-interpreted, and even more so by consumers. It may induce anxiety and do more harm than good.”
Professor Emad El-Omar, Editor In Chief of the journal GUT said few gastroenterologists would use the test as “hardly anyone would be able to interpret, with any certainty, what the results mean.”
“Until we have some evidence that certain microbiota signatures are predictive of disease course, its treatment or its response to manipulation, it is not wise to raise hopes too high or indeed create anxiety if the analyses show a less than favourable result.”
Professor El-Omar added: “I have a lot of respect for the people that developed this test but I caution against its use as a commercial test ready for the big time. We are not ready and everyone knows this. Let’s do the hard work and do some clinical trials and proper clinical research.”
Testing may be irrelevant
Nutritionist Dr Rosemary Stanton said patients did not need to know the composition of their gut biome to make lifestyle changes that would improve their gut health.
“We already know that healthy gut bacteria are important. It’s one of the reasons why the dietary guidelines recommend consuming more healthy plant foods, less junk food and only modest amounts of red meat,” she said.
“If people have digestive problems, they should see their GP. That is then the best person to decide whether such tests are appropriate,” she said.
“I do not recommend encouraging self-diagnosis – especially if it involves expensive tests which may be irrelevant for the particular problem. If the tests are useful, they should be reserved for those who really need them.”
For the curious
Dr Pribyl defended the company’s decision to offer the test direct-to-consumers.
“A lot of overseas companies are already offering gut biome testing direct-to-consumers but are providing over-extrapolated results from low-resolution data,” she said. “There has been so much media hype, we wanted to provide a product backed up by evidence.”
Other tests on the market are based on sequencing the 16S rRNA gene only, whereas Microba sequences the whole genome of the lower intestine’s microbiome.
Dr Pribyl added: “We are not recommending patients do this test instead of seeing a healthcare professional. This is just for people who are curious about what is happening in their gut or for healthcare professionals to use with complex patients.”
Customers also have the option of sharing their health data to assist further research.
Around 3000 kits have been sold since July, Dr Pribyl said, “to a mix of people – probably some ‘worried well’, but also to specialists including gastroenterologists and allied health practitioners.”
Microba is offering a free course for healthcare professionals about the gut biome. The company is also currently working on a product specifically for healthcare professionals, however, Dr Pribyl said regulatory hurdles meant it would be a few years before this was available.
Professor Ian Frazer was not available for an interview but said in a statement Microba had a long- term commitment to advancing the current growing knowledge of how the constituents of the gut microbiome can impact on human health.
“This knowledge will determine how and when we should incorporate the new technology of metagenomic classification of mixed microbial environments into routine patient care,” he said.
Professor Frazer is a board member and shareholder in Microba and comments attributed to him are his own, and should not be held to be representing the views of any employer.