Bowel preparation for colonoscopy: relevant for the gut’s microbiota?

Potential contributions of the host-associated gut microbiota to human physiology continue to receive extensive research interest. While various lines of evidence support a role of the microbiota in maintaining human health, perturbations in normal microbiota composition have been correlated with various dietary changes and disease states,1 particularly diarrhoea.2 We have long known that close interactions between microbiota and the host’s immune system occur in the distal small intestine and that microbes are highly metabolically active in the proximal large intestine. Recent global efforts have accumulated a wealth of data on the diversity of human gut-associated microbiota. These studies confirmed that even in healthy individuals a large degree of intraindividual as well as interindividual variation in microbiota composition and although to a lesser degree, microbial activities occur. However, what represents ‘normal’ gut microbiota is still not fully understood, which is largely due to the observed variation within and among individuals. While recent work based on phylogenetic analysis of both the small subunit (16S) of ribosomal RNA as well as metagenomic datasets suggests the existence of …