In addition to dietary intake, the gut microbiome serves as an essential source of vitamins.72 Our data suggest that C. tropicalis MYA-3404 uses its nicotinamidase to modulate vitamin B3 metabolism, which is in line with findings in commensal bacteria.73 Studies have indicated the beneficial effects of nicotinic acid on chemical-induced colitis by inhibiting proinflammatory pathways by acting on their factors or cytokine production.74,75 We explored an additional role of nicotinic in inducing IL-17A expression for promoting epithelium proliferation that ameliorates intestinal inflammation. This evidence concerns the gene IL17A and colitis.