During the last 15 years, a myriad of studies have shed light on the beneficial effects of some microorganisms, such as the genres Lactobacilli or Bifidobacteria, commonly found, for instance, in fermented dairy. Overall, what scientists have learnt during the last decade is that gut microbiota has to be balanced, rich and diverse to stay in good health.

In this sense, as we explained in this blog, you can buy fecal microbiota simple testing kits online that offer a quick wellness test via stool samples and let you know more about your gut microbiota.

But, what information do they give? Does general public know how to interpret it?

Can these tests help doctors in their daily practice? Who should take a stool test and who should prescribe it?

To answer all these questions and talk about stool and microbiota testing, to know more about it and its limits, we interviewed three experts from this field who have different views: Andrea Hardy, a registered dietitian from Calgary (Canada); Fernando Azpiroz, a gastroenterologist at Hospital Universitari Vall d’Hebron in Barcelona (Spain); and Joël Doré, Research Director at the French National Research Institute for Agriculture, Food and the Environment, INRAE.


What can health care professionals learn from these tests?

Joël Doré: The domain is still in its infancy and its teaching is not yet developed in medical training. Hence, health care professionals learn more about the microbiome from scientific publications, books, scientific meetings, massive open online courses (such as MOOCs) and the Gut Microbiota for Health website than during their medical education. This is slowly changing but scientific knowledge expands much faster than training programs can adapt to.

Fernando Azpiroz: For health care professionals, these tests have no use at all. At this moment, they are only useful for research. Moreover, there are few labs that can make proper analysis and interpret correctly the very complex statistics. It is not about finding the presence of a particular bacteria or a group of bacteria. Gut microbiota is an ecosystem. It can be Mediterranean, tropical or a desert. The important thing is to be stable. A Mediterranean ecosystem is not better than a tropical one, they just work differently.


Apart from offering a gut microbiota profile, can these tests give us information about our metabolism, for instance?

Joël Doré: Yes! In spite of the limitations detailed above, most techniques will give an indication of the type of microbiota and should highlight some genera or even species of bacteria that may be known for their functions and contributions to health. Inference of the production of beneficial or detrimental metabolites may be delicate, but some of these metabolites can be analysed directly.

Andrea Hardy: Presence of bacteria may not mean function. As we uncover more about the gut microbiota, it appears how bacteria work together as an ecosystem influence health outcome. While presence of bacteria and their metabolites are interesting, we can’t possibly make health recommendations around those when we don’t fully understand the implications of those markers. Another major concern I have is that many of the commercially available testing kits use animal research to support their recommendations, which is a great place to start for research, but certainly not for making human recommendations.


In this sense, is stool testing a tool that we can expect to be used for professional medical practice in the future to measure some markers and adapt the advice given to patients?

Joël Doré: This will undoubtedly come with a few more years of research and clear substantiation of usefulness in various clinical conditions. For example, microbiome richness (biodiversity, in a way) has often been documented as a strong indicator of a healthier situation, much like for natural ecosystems. Diet and lifestyle recommendations may not require stool testing, except maybe to obtain evidence of their impact.

To go one step further, as we are microbial, what really matters is the quality of the interactions between our microbiota and our cells and organs: our gut but also our liver, muscles or brain. My guess is that the future of testing will expand to assessing the quality of these host-microbe interactions.

Andrea Hardy: I’m hoping so! I think we’re much closer with using the gut microbiota to predict blood glucose response in a patient population than general testing of presence of bacteria or metabolites and can see that being incorporated into practice as more data comes out. Bottom line: For these tests to be useful in health care, we need data to support that doing the test and making changes based on that test exceed outcomes in comparison to traditional dietary therapy – otherwise the tests are redundant.