Impact of Diet on Gut Microbiota in Diverticular Disease of the Colon: An Exploratory Retrospective Study.

Symptomatic uncomplicated diverticular disease (SUDD) is the primary clinical manifestation of diverticular disease (DD). Although gut microbiota (GM) perturbation and dietary habits are considered important factors in the development of the disease, there is currently a lack of data on the potential relationship between diet, GM profile and SUDD. An exploratory retrospective study was conducted in a SUDD cohort of 47 patients to investigate this relationship; a diverticulosis cohort of 19 patients served as the control group. Patients were stratified by their self-reported dietary habits, i.e., Mediterranean diet, predominantly plant-based diet or omnivorous diet. GM was profiled using 16S rRNA amplicon sequencing of fecal swabs. SUDD patients following a Mediterranean or predominantly plant-based diet showed higher alpha diversity and enrichment of known fibre degraders and short-chain fatty acid producers, such as members of the Lachnospiraceae, Ruminococcaceae, Oscillospiraceae and Prevotellaceae families. This suggests that their gut (and whole-body) health is less impaired. In contrast, those following an omnivorous diet showed an increased presence of pro-inflammatory taxa, including the mucus degrader R. torques, which suggests impaired gut barrier function and potential systemic implications. Similar associations between GM profile and dietary habits were found when considering SUDD patients with moderate abdominal pain severity (according to visual analogue scale, VAS) and those scored as DICA 1 according to the endoscopic severity of the disease. However, no such associations or trends were observed in SUDD patients scored as DICA 2, which suggests that diet may be unable to impact GM dysbiosis as SUDD severity increases. Despite the study's limitations, primarily its retrospective design and related biases, our findings suggest that other GM modulation tools should be employed in more severe cases of SUDD to reverse dysbiosis while alleviating symptoms.