Does Vitamin D Supplementation Impact Fibromyalgia-Related Pain? A Systematic Review and Meta-Analysis

Background: Fibromyalgia is a chronic condition characterized by widespread pain, fatigue, and localized tenderness. Its pathophysiology remains unclear, and treatment options are often limited and only partially effective. Recent studies suggest a potential link between vitamin D deficiency and symptom severity, as vitamin D may play a role in modulating pain and inflammation. Methods: This systematic review and meta-analysis assessed the efficacy of vitamin D supplementation in reducing pain and improving quality of life in fibromyalgia patients, focusing on studies up to 31 December 2024. Following PRISMA guidelines, a literature search in PubMed, Web of Science, and Scopus identified 2776 articles; 7 were included in the systematic review and 4 studies in each meta-analysis. Results: Results showed that vitamin D supplementation significantly reduced pain levels compared to the control group, with a statistically significant effect observed using the NRS or VAS (SMD = −0.85; 95% CI: −1.54 to −0.17; p = 0.0148), as well as the FIQ scale (SMD = −0.87; 95% CI: −1.56 to −0.20; p= 0.0115), resulting in an improvement in quality of life. Conclusions: These findings suggest that vitamin D may be a valuable adjunct in fibromyalgia management, particularly for pain. However, further high-quality trials are needed to confirm these effects and identify responsive patient subgroups.