https://www.ncbi.nlm.nih.gov/pubmed/29118054 BMJ Open. 2017 Nov 8;7(11):e015296. doi: 10.1136/bmjopen-2016-015296. Vitamin D status in chronic fatigue syndrome/myalgic encephalomyelitis: a cohort study from the North-West of England. Earl KE1, Sakellariou GK1,2, Sinclair M1, Fenech M1,3, Croden F4, Owens DJ5, Tang J6, Miller A3, Lawton C4, Dye L4, Close GL5, Fraser WD6, McArdle A1, Beadsworth MBJ1,3. Author information Abstract OBJECTIVE: Severe vitamin D deficiency is a recognised cause of skeletal muscle fatigue and myopathy. The aim of this study was to examine whether chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) is associated with altered circulating vitamin D metabolites. DESIGN: Cohort study. SETTING: UK university hospital, recruiting from April 2014 to April 2015. PARTICIPANTS: Ninety-two patients with CFS/ME and 94 age-matched healthy controls (HCs). MAIN OUTCOME MEASURES: The presence of a significant association between CFS/ME, fatigue and vitamin D measures. RESULTS: No evidence of a deficiency in serum total 25(OH) vitamin D (25(OH)D2 and 25(OH)D3 metabolites) was evident in individuals with CFS/ME. Liquid chromatography tandem mass spectrometry (LC-MS/MS) analysis revealed that total 25(OH)D was significantly higher (p=0.001) in serum of patients with CFS/ME compared with HCs (60.2 and 47.3 nmol/L, respectively). Analysis of food/supplement diaries with WinDiets revealed that the higher total 25(OH) vitamin D concentrations observed in the CFS/ME group were associated with increased vitamin D intake through use of supplements compared with the control group. Analysis of Chalder Fatigue Questionnaire data revealed no association between perceived fatigue and vitamin D levels. CONCLUSIONS: Low serum concentrations of total 25(OH)D do not appear to be a contributing factor to the level of fatigue of CFS/ME.