High Dose Vitamin D supplementation alters faecal microbiome and predisposes mice to more severe colitis.

Abstract

Vitamin D has been suggested as a possible adjunctive treatment to ameliorate disease severity in human inflammatory bowel disease. In this study, the effects of diets containing high (D++, 10,000&#x2009;IU/kg), moderate (D+, 2,280 IU/kg) or no vitamin D (D-) on the severity of dextran sodium sulphate (DSS) colitis in female C57Bl/6 mice were investigated. The group on high dose vitamin D (D++) developed the most severe colitis as measured by blinded endoscopic (p&#x2009;<&#x2009;0.001) and histologic (p&#x2009;<&#x2009;0.05) assessment, weight loss (p&#x2009;<&#x2009;0.001), drop in serum albumin (p&#x2009;=&#x2009;0.05) and increased expression of colonic TNF-&#x3b1; (p&#x2009;<&#x2009;0.05). Microbiota analysis of faecal DNA showed that the microbial composition of D++ control mice was more similar to that of DSS mice. Serum 25(OH)Dlevels reduced by 63% in the D++ group and 23% in the D+ group after 6 days of DSS treatment. Thus, high dose vitamin D supplementation is associated with a shift to a more inflammatory faecal microbiome and increased susceptibility to colitis, with a fall in circulating vitamin D occurring as a secondary event in response to the inflammatory process.