What role does MTHFR play in Müdigkeit?

MTHFR (methylenetetrahydrofolate reductase) is a key enzyme in folate metabolism and homocysteine regulation. The common C677T variant reduces enzyme activity by 30–70%, potentially raising homocysteine levels – a risk factor for fatigue, cardiovascular issues, and neurological symptoms. However, the direct link between MTHFR variants and fatigue is not firmly established. Many individuals with C677T have normal homocysteine and no symptoms. Fatigue can also stem from iron deficiency, thyroid problems, or sleep disorders. Clinical relevance is often overstated by marketing. A homocysteine blood test is advisable; only if elevated might methylfolate or vitamin B12 supplementation be considered. Without lab values, MTHFR's role in fatigue remains speculative. Evidence is based on observational studies and GWAS, not randomized controlled trials.