Now that the importance of our gut microbes has become widely known, at least generally, many people are wondering about the state of their own microbe communities, and what they should be doing to improve them. This is a question I have often been asked, and my answer has been that we just don't know enough to make recommendations, beyond eat lots of fiber and fresh veggies, and manage stress. But now several companies are offering tests you can take at home by collecting samples of your poop and sending them to the companies. The tests can cost between $100 and $1000.
Can you really find out useful information about your gut microbiome from these at-home tests? Can they tell you what lifestyle changes you should make?
Well, actually… no.
As reported in The Scientist (a features and news magazine targeted for professional scientists) by Sneha Khedkar, "regulatory gaps plague at-home microbiome kits." In fact, the tests are not regulated or standardized at all. The companies claim that they are not diagnosing anything, so these tests are not "in vitro diagnostic devices." "In vitro diagnostic devices" are regulated by the Food and Drug Administration and are required to provide evidence of accuracy and reliability of their results.
Are these gut microbe tests accurate and reliable?
When investigators with the National Institute of Standards and Technology (NIST) mailed a standardized poop sample to seven different companies, they got some dramatically different results from each lab.The researchers attribute this to the fact that the labs were not using the same methodology. There is a movement within the industry to standardize techniques, and thus it would seem wise to wait to try one of the at-home gut microbe tests until such standardization occurs.
For me, an equally important problem is the fact that even if the test were reliable, we don't know enough about the gut microbe communities to be able to say, for apparently healthy people, that there is anything "good" or "bad" about the specific species living in your gut, as long as you have sufficient diversity. As one gastroenterologist put it — "we don't even know what a normal microbiome is." And even knowing the range of "normal," the important thing is — what are they doing? What they are doing likely relates to the other species around, as well as features of your gut immune system (e.g., genetics and whether it is generally in a tolerant or intolerant state). What we do know is that the interactions can be complex. Clinicians are concerned that decisions, for instance about diet, made based on poorly understood microbiome profiles could be harmful, and I worry about that too.