Oral Microbial Diversity is Associated with Biologic Treatment and Metabolic Health Status but not with Disease Activity in Patients with Inflammatory Bowel Disease.

Background: Higher diversity of the oral microbiome has been associated with poorer oral health outcomes in the general population. We aimed to characterize the oral microbiota in patients with inflammatory bowel disease (IBD) and compare this with that of healthy controls (HC). We also sought to examine associations between IBD management and disease control, diet and metabolic disease with oral microbial diversity. Methods: This prospective case-control study compared participants with IBD in clinical remission with HC. Baseline anthropometry and fasting blood metabolic markers were measured, dietary intake recorded, and oral samples were collected for 16S rRNA gene amplicon sequencing. Results: There were 57 patients with IBD (Ulcerative colitis (UC) = 26, Crohns Disease (CD) = 31) and 24 HC enrolled. There were no significant differences in oral microbial diversity between the IBD and HC cohorts. Among participants with IBD, oral microbial diversity did not associate with IBD activity nor risk of subsequent disease flare (adj- Conclusions: Oral microbial diversity is not associated with IBD disease activity or course but is positively influenced by biologic treatment. Higher fasting insulin, however, is associated with more diverse "unhealthy" oral microbiota. Within the limitations of this small study, oral microbiota may be a better marker of metabolic health than of IBD activity.