Is hypovitaminosis D associated with fibromyalgia? A systematic review.

ABSTRACT

CONTEXT Recent findings have suggested a high prevalence of vitamin D deficiency or insufficiency in fibromyalgia (FM) patients despite the lack of clinical and pathophysiological evidence. OBJECTIVE: A systematic review was conducted to examine the association between vitamin D status and FM, including the effect of vitamin D supplementation. DATA SOURCE PubMed, LILACS, Scopus, SciELO, Cochrane, and EMBASE were searched, from January 2000 to July 2018, using the descriptors "Fibromyalgia" and "Vitamin D." STUDY SELECTION Trials including FM patients in whom vitamin D levels were assessed were eligible for inclusion. DATA EXTRACTION Data comprised age, gender, country, aims, bias, diagnosis criteria, cutoff point, and status of vitamin D, together with FM symptoms and vitamin D supplementation protocol. RESULTS: A total of 26 articles were selected. Most of the studies were found to present unreliable control groups and small samples. Experimental data on vitamin D supplementation indicated improvement in certain FM symptoms. CONCLUSION: Prevalence of hypovitaminosis D in the FM population and the cause-effect relationship were inconclusive. Nevertheless, vitamin D supplementation may be considered as a co-adjuvant in FM therapy.