Fosså, Alexander, Smeland, Knut Halvor, Fluge, Øystein et al. · PloS one · 2020 · DOI
This study looked at blood chemicals called amino acids and B vitamins in lymphoma survivors who experienced lasting fatigue after cancer treatment. Researchers found that people with this fatigue had lower tryptophan (an amino acid) and signs of ongoing low-level immune activation and inflammation. The study suggests that persistent tiredness after lymphoma treatment may be caused by the body's immune system staying activated longer than expected.
This study identifies potential biological mechanisms underlying post-cancer fatigue through metabolite analysis, offering insights into immune activation and tryptophan metabolism that may be relevant to ME/CFS pathophysiology. Finding metabolic and immune markers associated with chronic fatigue in cancer survivors strengthens the case that chronic fatigue syndromes have measurable biological underpinnings, supporting the need for biomarker-driven diagnostic and therapeutic approaches.
This study does not prove that low tryptophan or elevated B6 catabolism *cause* chronic fatigue—only that they correlate with it. The cross-sectional design cannot establish temporal relationships or rule out that fatigue itself drives these metabolic changes. Results are specific to lymphoma survivors after stem cell transplantation and may not generalize to other cancer types or ME/CFS populations without independent validation.
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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