Exploiting the gut microbiota's fermentation capabilities towards disease prevention.

One of the crucial roles played in the context of human physiology by the human gut microbiota is to ferment resistant polysaccharides and dietary fibres in the colon. Even though it has long been presumed that these processes play fundamental roles in regulating human health, we remain unable to treat or even diagnose deficiencies in microbial fermentation. In part, this relatively slow progress can be attributed to the fact that studying the gut microbiota and its metabolic properties has until now heavily relied on next generation sequencing and case-control cohorts to identify differentially abundant genes, pathways or organisms in the context of a particular clinical indication. Unfortunately, these methods and studies do not allow us to rigorously probe the functional and metabolic phenotype of a microbiota, or for elucidating its mechanisms of action on the host. To improve our clinical control over these fermentation processes, it is critical that we improve our quantitative, mechanistic understanding of their impact on host physiology. In this review, we provide an overview of our current understanding of the roles microbial fermentation processes play in human health in the context of disease prevention. We then describe the evidence linking these processes with depression and anxiety-related conditions, and use these complex disorders as a framework for illustrating the fact that achieving a clinical vision that exploits microbial fermentation towards human health will depend on thoughtful multi-disciplinary collaboration between clinical research, systems biology, and the pharmaceutical and analytical sciences.