Diverticulosis is not associated with altered gut microbiota nor is it predictive of future diverticulitis: a population-based colonoscopy study.

BACKGROUND: The etiopathogenesis of diverticular disease is unknown. OBJECTIVE: To compare the fecal and mucosa-associated microbiota between participants with and without diverticulosis and participants who later developed diverticulitis versus those that did not from a population-based study. METHODS: The PopCol study, conducted in Stockholm, Sweden, invited a random sample of 3556 adults to participate, of which 745 underwent colonoscopy. Overall, 130 participants (17.5%) had diverticulosis. 16S rRNA gene sequencing was conducted on available sigmoid biopsy samples from 529 and fecal samples from 251 individuals. We identified individuals who subsequently developed acute diverticulitis up to 13 years after sample collection. In a case-control design matching for gender, age (+/-5 years), smoking and antibiotic exposure, we compared taxonomic composition, richness and diversity of the microbiota between participants with or without diverticulosis, and between participants who later developed acute diverticulitis versus those who did not. RESULTS: No differences in microbiota richness or diversity were observed between participants with or without diverticulosis, nor for those who developed diverticulitis compared with those who did not. No bacterial taxa were significantly different between participants with diverticulosis compared with those without diverticulosis. Individuals who later developed acute diverticulitis (2.8%) had a higher abundance of genus Comamonas than those who did not (p = .027). CONCLUSIONS: In a population-based cohort study the only significant difference was that those who later develop diverticulitis had more abundance of genus Comamonas. The significance of Comamonas is unclear, suggesting a limited role for the gut microbiota in the etiopathogenesis of diverticular disease.

The gut microbiota and mental health in adults.

A growing body of evidence point toward the bidirectional gut microbiota-brain axis playing a role in mental health. Most of this research is conducted on animals why we in this review summarize and comment upon recent studies evaluating the gut microbiome in mental health in humans. Further support for the relevance of the bidirectional gut microbiota-brain communication in mood disorders has been presented, such as the effect of probiotics on brain connectivity and mental health outcomes and pregnancy related stress on gut microbiota in the newborn child. However, the heterogeneity between studies precludes conclusions regarding differences in microbiota composition in mental disease and health and many of the studies are limited by a cross-sectional design, small sample sizes and multiple comparisons. Thus, well-designed longitudinal studies with larger sample size, accounting for confounders are needed.