At-Home Microbiome Tests: Science or Snake Oil?

While the gut microbiome is absolutely real, incredibly complex, and an important area of research, we still don’t fully understand it, and there are many problems with the claims these testing companies make.

First of all, there is no universally accepted definition of a “healthy” microbiome.¹ What’s normal for one person may be abnormal for someone else.² Additionally, your microbiome can rapidly change depending on what you ate the day before. That makes interpreting these results problematic.

If there is that much individual variability, you can’t standardize what is normal and what is not. For example, a normal serum sodium level for most healthy adults around 135-145 milliequivalents per liter. If I have a patient in the emergency department with a new sodium change of 120 meq/L or 155 meq/L, I know this is very abnormal and I need to address this problem. We don’t have any data like that when it comes to a microbiome.

Next, there is no standardized way of obtaining and testing the samples.³ Let’s stick with the serum sodium level as an example. Obtaining blood is very standardized and protocolized. The skin is cleaned and punctured in a standardized fashion. The volume of blood and the tube the blood goes is defined by a protocol. The machines that analyze the blood are required to meet very specific criteria and are tested regularly for accuracy. This is mandated by the United States Centers for Medicare and Medicaid through the Clinical Laboratory Improvement Amendments program. If labs don’t comply, they face heavy fines and can be shut down. Nothing like this exists with at-home microbiome testing.

Even if we had established normal and abnormal results, along with a standardized way of collecting and analyzing samples, we still don’t have enough data on how to apply the information obtained through testing. Expert panels have noted that the recommendations provided by these companies are not supported by robust scientific evidence. And while there is emerging research on role of the microbiome in nutrition and mental health, the field is not yet at a stage where actionable, individualized recommendations can be reliably made on current technologies.^4,5 Even researchers of The Integrative Human Microbiome Project (yes, there’s huge NIH-funded research in this field) state they are in the very early stages of understanding how the microbiome works, how it influences health, and that it’s too early to use any of it for individualized care.⁶

If you need further evidence, here’s one that speaks volumes. There is no major pharmaceutical company cashing in on microbiome-targeted drugs for individualized care. As much as I dislike the profit margins of big pharma, I appreciate that they are under close scrutiny by the FDA and can’t make money from claims that are not supported by evidence. If they are not making money off individualized microbiome testing, it’s because there is not enough evidence to support it. They would be first in line if there were.