Scientists gave the same sample to seven home microbiome tests. The results varied dramatically
The science and regulations supporting these tests “do not yet exist,” the researchers say.
Trillions of microbes influence the functioning of our digestive system, but testing them can be a challenge.
Katerina Kon/Science Photo Library/Getty Images
From drinking celery juice to reducing diet to eating a handful of probiotic-rich foods like kimchi, gut health is at the top of the wellness agenda. And as you try to help your good bacteria thrive, home testing companies are thriving that claim to open the black box of digestive health.
It’s easy to understand why we’ve become so fascinated by our gut. Scientists have long known that vast colonies of bacteria, viruses, and other microorganisms – a population collectively called the microbiome – live on and inside the human body. But how they affected our health was a mystery for a long time. Over the past few years, we’ve learned that myriad factors, from the food we eat to the time we spend sleeping and our genes to the home we live in, all influence our microbiome. And this, in turn, can affect our immunity, digestion, aging, and even our emotions.
And that’s why at-home microbiome testing has evolved so rapidly billion dollar market. But today a study was published communication biology Some of these tests suggest insights It may not be as accurate as they claim.
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“At least in the public imagination, the gut microbiome has been linked to the idea that you can improve a whole range of conditions through diet and lifestyle changes,” says Dianne Hoffman, co-author of the study and a professor of health law at the University of Maryland, Baltimore. “There’s been a lot of publicity about him, but the publicity doesn’t really match the evidence.”
According to Hoffman and his co-authors, at-home microbiome tests “straddle the line” between medical and wellness products, placing them in a legal gray area. Currently, there are no microbiome diagnostic tests approved by the Food and Drug Administration for clinical use in the U.S., even as the market for at-home versions is growing.
These direct-to-consumer microbiome tests rely on the user to collect their own stool samples at home – essentially scooping their own stool into a vial and sending it to a lab for analysis. Stool samples are an effective way to determine which microbes are present in the digestive tract. But different parts of the sample and different methods of storing or processing it can give dramatically different results. To get a clearer idea of how capable the home tests were, Hoffman and his team created a test stool sample by mixing healthy fecal matter until the mixture of organisms was uniform.
The research team then randomly selected seven different companies – none of which are named in the study – and collected samples from the same initial fecal source, following the companies’ collection methodology. The team completed and sent back three separate tests to each company. This allowed researchers to compare results from different companies and test whether each company’s analysis was accurate enough to yield similar results from all three versions of the sample.
The results were even more uneven than the team expected. Of the more than 1,200 taxonomic groups of microbes identified by all tests combined, only three microbial genera were present in the results from all seven companies. Even tests processed by the same company do not always match.
In one case, a company sent back the results of three different tests, two of which described that version of the sample as “healthy” and one of which described it as “unhealthy.” Such outlier results make the uncertainties of the tests clear, says Scott Jackson, co-author of the study and a former employee of the National Institute of Standards and Technology. “You can see it stands out like a sore thumb.”
The researchers caution that people who employ these direct-to-consumer tests should not use the results to inform lifestyle changes or medical decisions — especially until the assay is potentially supported by more research and regulation.
“As a scientific field it’s still relatively nascent,” Jackson says. “I think we’ll figure it out, but we’re not there yet.”
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