Can low vitamin D levels cause chronic fatigue syndrome?

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  • Patients with chronic fatigue syndrome/myalgic encephalomyelitis (CFS/ME) do not exhibit insufficient concentrations of circulating total 25-hydroxyvitamin D [25(OH)D]; however, the values were significantly higher compared with control participants.

Why this matters

  • Despite non-scientific media interest, limited data exist examining circulating concentration of vitamin D metabolites in patients with CFS/ME.

Key results

  • No deficiency in serum total 25(OH)D [25(OH)D2 and 25(OH)D3 metabolites] was evident in patients with CFS/ME.
  • Compared with control participants, total serum 25(OH)D concentration was significantly higher (P=.001) in patients with CFS/ME (47.3 nmol/L vs 60.2 nmol/L, respectively).
  • Compared with control participants, the average vitamin D intake through the use of supplements was higher (P=.05) in patients with CFS/ME (0.6±1.7 vs 4.9±9.7 µg/d, respectively).
  • Analysis of Chalder Fatigue Questionnaire data demonstrated no association between perceived fatigue and vitamin D levels in patients with CFS/ME with high or low total 25(OH)D concentration.

Study design

  • Study evaluated 92 patients with CFS/ME and 94 age-matched control participants to investigate the association between CFS/ME and vitamin D measures.
  • Funding: British Medical Research Council; ME Association; University of Liverpool.


  • Majority of participants were Caucasians, hence findings may not reflect all CFS/ME populations.