Vermeulen, Ruud C W, Scholte, Hans R · Psychosomatic medicine · 2004 · DOI
This study tested whether two types of carnitine supplements—acetylcarnitine, propionylcarnitine, or both together—could help reduce fatigue in ME/CFS patients. Over 24 weeks, about 59–63% of patients taking either supplement alone reported significant improvement in fatigue and concentration, though acetylcarnitine worked better for mental fatigue while propionylcarnitine worked better for general fatigue. Unfortunately, most patients experienced worsening fatigue within 2 weeks after stopping treatment.
Carnitine metabolism has been hypothesized as abnormal in ME/CFS, making this one of the early targeted supplementation trials for the condition. The differential effects of two carnitine forms on different fatigue types provide mechanistic clues about how metabolism might contribute to ME/CFS symptoms. However, the rapid relapse after treatment cessation suggests any benefit may not be sustained without ongoing therapy.
This study does not prove carnitine supplements cause long-term improvement or are superior to placebo, as the open-label design without blinding cannot exclude placebo effect. The short follow-up period (2 weeks post-treatment) does not establish whether benefits persist with continued use or reflect lasting metabolic correction. Correlation between plasma carnitine levels and improvement in only the acetylcarnitine group suggests the mechanism remains unclear.
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
Vermeulen, Ruud C W & Scholte, Hans R (2004). Exploratory open label, randomized study of acetyl- and propionylcarnitine in chronic fatigue syndrome.. Psychosomatic medicine. https://doi.org/10.1097/01.psy.0000116249.60477.e9
BibTeX
@article{mecfsatlas-vermeulen-2004-exploratory-open,
author = {Vermeulen, Ruud C W and Scholte, Hans R},
title = {Exploratory open label, randomized study of acetyl- and propionylcarnitine in chronic fatigue syndrome.},
journal = {Psychosomatic medicine},
year = {2004},
doi = {10.1097/01.psy.0000116249.60477.e9},
note = {PubMed: 15039515},
url = {https://www.mecfsatlas.com/evidence/vermeulen-2004-exploratory-open},
}Atlas snapshot reference
ME/CFS Atlas. Generator v1 / Scanner v1.4 / policy v0.1. Accessed 2026-05-25. https://www.mecfsatlas.com/evidence/vermeulen-2004-exploratory-open
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