Efficacy of Vitamin D Supplementation in the Improvement of Clinical Status in Patients Diagnosed with Fibromyalgia Syndrome: A Systematic Review

Background: Fibromyalgia syndrome is characterised by extensive muscular pain and chronic fatigue. Among the pharmacologic and other nutrient supplements that have been studied, Vitamin D has garnered attention owing to the critical role it plays in inflammatory and pain pathways. We conducted a systematic literature review to examine the efficacy of vitamin D supplementation in improving the clinical status of the patients and alleviating the symptoms of fibromyalgia. Methods: We searched Cochrane CENTRAL, PubMed, Science Direct, Scopus, grey literature (medrXiv and biorXiv) for observational studies, randomized controlled trials, case-control studies, and case reports published in English from January 2011 to May 2021, using the terms vitamin D and fibromyalgia or FMS. References were reviewed manually and articles were only included if they were specific about the diagnosis of fibromyalgia. Results: 2651 studies were retrieved, with 12 studies fulfilling the inclusion criteria. 11 out of these 12 studies were of high quality and showed low risk of bias. 11 of these also demonstrated definitive improvement in clinical status and various outcome measures following supplementation with Vitamin D. Conclusion: Our study emphasises an association between supplementation of vitamin D and improvement of the clinical condition of fibromyalgia through a systematic review of high-quality studies. The study also identified areas for future scope for research needed for standardising the detection and treatment of this chronic condition through cost-effective supplements such as Vitamin D.