The role of vitamin D testing and replacement in fibromyalgia: a systematic literature review

Background Fibromyalgia is a debilitating condition, characterized by extensive muscular pain and fatigue. Vitamin D is essential for overall health, with ubiquitous involvement in various inflammatory and pain pathways. Little is known about its role in fibromyalgia. We performed a systematic literature review to determine if vitamin D contributes to the pathology and disability of patients with fibromyalgia, and to assess the role of vitamin D supplementation in disease management.Methods We searched Medline, EMBASE and the Cochrane Library for clinical studies and randomized controlled trials published in English during January 2000 to June 2017, using the terms vitamin D or hypovitaminosis D combined with fibromyalgia or FMS. References were reviewed manually and articles were only included if they were specific in their diagnosis of fibromyalgia and used appropriate control groups.Results Four hundred and sixty-six studies were retrieved, of which fourteen fulfilled the inclusion criteria. Six studies, of which two had the best quality evidence, found that patients with fibromyalgia have low levels of vitamin D compared to healthy controls. Conflicting results were obtained on the effect of vitamin D on pain or symptom control, with no clear consensus as to the role of supplementation in the management of fibromyalgia.Conclusions Our results highlight an association between vitamin D deficiency and fibromyalgia. However, its role in the pathophysiology of fibromyalgia and the clinical relevance of identifying and treating this requires further elucidation with appropriately controlled studies.