Effects of Vitamin D Supplementation on Inflammatory Markers in Multiple Sclerosis Patients: A Systematic Review and Meta-analysis

Context: Numerous studies have indicated that vitamin D can modulate the immune system and plays an important role in regulating immune cells’ functions. Some clinical studies have assessed the effect of vitamin D supplementation on cytokine markers in multiple sclerosis (MS) as a disease in which the immune system’s function is disrupted. Evidence Acquisition: This study was designed to assess randomized clinical trial studies evaluating the overall effect of vitamin D on the levels of IL-10, IL-17, and IFN-γ in MS patients. Methods: We searched PubMed and Scopus online databases up to November 2020 for relevant randomized clinical trial studies by using certain keywords. Eight studies from 273 articles, with a total sample of 443 participants, were considered Results: The meta-analysis indicated that vitamin D consumption did not significantly change the levels of IL-10 (WMD : -174.56, 95% CI: -373.10 to 23.98), IL-17 (WMD : -0.11, 95% CI: -0.54.10 to 0.33), or IFN-γ (WMD : 61.47, 95% CI: 43.96 to 78.98) in MS patients. Conclusions: Further clinical trials are warranted to evaluate the effects of vitamin D supplement on IL-10 and IL-17, and INFγ levels in MS patients.