Earl, Kate E, Sakellariou, Giorgos K, Sinclair, Melanie et al. · BMJ open · 2017 · DOI
This study investigated whether low vitamin D levels contribute to the fatigue experienced by people with ME/CFS. Researchers compared 92 ME/CFS patients with 94 healthy controls and found that ME/CFS patients actually had higher vitamin D levels, often because they were taking vitamin D supplements. Importantly, there was no connection between vitamin D levels and how fatigued patients felt, suggesting that vitamin D deficiency is not a cause of ME/CFS fatigue.
Since severe vitamin D deficiency is known to cause muscle fatigue and myopathy, this study addresses an important question about whether correcting vitamin D status could improve ME/CFS symptoms. The findings suggest that vitamin D supplementation alone is unlikely to resolve fatigue in ME/CFS patients, helping redirect research and clinical efforts toward other potential biological mechanisms.
This study does not prove that vitamin D plays no role in ME/CFS; it only shows that baseline deficiency is not a primary contributor to fatigue severity in this cohort. The cross-sectional design cannot determine causality or whether vitamin D supplementation might help a subset of patients with very low baseline levels. The study also does not address other forms of vitamin D metabolism or tissue-level vitamin D status.
About the PEM badge: “PEM required” means post-exertional malaise was an explicit required diagnostic criterion for participant inclusion in this study — not that PEM was studied, observed, or discussed. Studies using criteria that do not require PEM (e.g. Fukuda, Oxford) are tagged “PEM not required”. How the atlas works →
The first block is for the primary paper and is the citation you should use in research work. The atlas-snapshot line only applies if you are specifically referring to this atlas’s reading of the paper on the date shown.
Primary citation
Earl, Kate E, Sakellariou, Giorgos K, Sinclair, Melanie, Fenech, Manuel, Croden, Fiona, Owens, Daniel J, et al. (2017). Vitamin D status in chronic fatigue syndrome/myalgic encephalomyelitis: a cohort study from the North-West of England.. BMJ open. https://doi.org/10.1136/bmjopen-2016-015296
BibTeX
@article{mecfsatlas-earl-2017-vitamin-status,
author = {Earl, Kate E and Sakellariou, Giorgos K and Sinclair, Melanie and Fenech, Manuel and Croden, Fiona and Owens, Daniel J and Tang, Jonathan and Miller, Alastair and Lawton, Clare and Dye, Louise and Close, Graeme L and Fraser, William D and McArdle, Anne and Beadsworth, Michael B J},
title = {Vitamin D status in chronic fatigue syndrome/myalgic encephalomyelitis: a cohort study from the North-West of England.},
journal = {BMJ open},
year = {2017},
doi = {10.1136/bmjopen-2016-015296},
note = {PubMed: 29118054},
url = {https://www.mecfsatlas.com/evidence/earl-2017-vitamin-status},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-29. https://www.mecfsatlas.com/evidence/earl-2017-vitamin-status
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