The Crucial Role of Vitamin D in Regulating Gut Microbiota in Inflammatory Bowel Disease

In recent years, there has been an alarming increase in the incidence of inflammatory bowel disease (IBD), which includes both Crohn's disease (CD) and ulcerative colitis (UC), particularly in Western countries. This chronic condition is intricately linked to the composition and health of the gut microbiota (GM) — a complex community of microorganisms residing in the gastrointestinal (GI) tract. Despite extensive research, the underlying pathogenesis of IBD remains poorly understood, making it a wide area of investigation. This review aims to provide a comprehensive exploration of the complex relationship between GM and the onset and progression of IBD. A key focus is the nucleotide-binding oligomerization domain-containing protein 2 (NOD2) pathway, which plays a crucial role in the immune response to gut bacteria and may influence susceptibility to IBD. Through a review of the current literature, an attempt was made to understand how a gut microbiome (GM) imbalance – dysbiosis – can trigger the inflammatory processes associated with IBD. Moreover, this review highlights the crucial role of vitamin D (VitD), a fat-soluble vitamin that is often deficient in individuals affected by IBD. Research suggests that VitD deficiency may impair the immune system and disrupt GM health, contributing to disease severity. Additionally, a growing body of evidence indicates that VitD metabolism is involved in NOD2 regulation. VitD supplementation could potentially act as a therapeutic strategy for managing IBD, alleviating symptoms and enhancing the overall gut health. This study aims to improve our understanding of the connection between gut bacteria, the immune system, and nutrition, ultimately paving the way for more effective prevention and treatment strategies for IBD.