Cox, I M, Campbell, M J, Dowson, D · Lancet (London, England) · 1991 · DOI
This study tested whether people with ME/CFS have lower magnesium levels in their red blood cells and whether magnesium injections could help them feel better. Researchers compared 20 ME/CFS patients to 20 healthy people and found the patients did have lower magnesium. When 15 ME/CFS patients received weekly magnesium injections for 6 weeks, 12 reported feeling better with more energy and less pain, compared to only 3 out of 17 patients who received a placebo injection.
This study provides early evidence that magnesium deficiency may be involved in ME/CFS pathophysiology and suggests a potentially safe, inexpensive therapeutic intervention. The significant treatment effect (80% vs. 18% improvement) and documented correction of cellular magnesium in treated patients make this relevant for exploring metabolic and biomarker-driven approaches to ME/CFS management.
This study does not prove that magnesium deficiency causes ME/CFS, only that an association exists in this sample. The subjective nature of primary outcome measures (patient-reported wellbeing) without objective biomarkers of fatigue or dysfunction limits causal claims. The small sample size and single-site recruitment prevent generalization to all ME/CFS patients, and the mechanism by which magnesium improves symptoms remains unexplained.
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 →
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