["Probiotic medicine" and certainty of the evidence.]

These are excellent times for probiotic medicine. We have discovered more than 150,000 genomes of the microbiome, which can be aggregated into 4,930 species. However, the dream of microbiome-based medicine requires a new approach - an ecological and evolutionary understanding of host-microbe interactions, rather than a qualitative analysis of species. Yet researchers still disagree on what constitutes a healthy microbiome or how to define an altered one. There is still uncertainty as to which properties of the microbiome will represent the most informative biomarkers in clinical and epidemiological studies. And little is known about how the microbiomes of different regions of the body, such as the mouth, intestines or skin, interact. It is time to re-establish the foundations for the certainty of evidence in myocrobiome-based medicine. We believe robust new pillars are needed: starting clinical trials whenever possible; extending the role of N-of-1 trials; ending the "one probiotic for every disease" principle; reduce the number of outcomes of each research; search for the replicability of the results (the best test for the validity of an intervention with probiotics is not statistical significance but the replication of the result). Again, we would like to urge probiotic medicine researchers not to publish in "pirate" journals.