The Beneficial Role of Vitamin D in Interstitial Cystitis

Interstitial cystitis (IC) is a poorly understood chronic bladder disorder that is generally characterized by bladder discomfort and increased urination urgency and frequency. Vitamin D levels are associated with bladder pathology, and both rat and human bladders express receptors for vitamin D3. Vitamin D significantly reduced edema and bladder wall leukocyte infiltration in a IC animal model. Genetic studies have provided the opportunity to determine which proteins link vitamin D to IC pathology (i.e., the major histocompatibility complex (MHC) class II molecules, the transcription factor nuclear factor kappa B (NF-κB), RANTES (regulated on activation, normal T cell expressed and secreted), epidermal growth factor (EGF), transforming growth factor beta (TGF-β) family, and vascular endothelial growth factor (VEGF)). Vitamin D also exerts its effect on IC through non-genomic factors, i.e., Bacillus Calmette-Guérin (BCG) vaccination, mast cells and histamine, prostaglandins (PGs), reactive oxygen species (ROS), and inducible nitric oxide synthase (iNOS). Conclusion: Vitamin D may have a beneficial role in IC. Calcitriol is best used for IC because it is the active form of the vitamin D3 metabolite, and it modulates inflammatory cytokine expression. Further investigation with calcitriol in IC patients is needed.