Is MTHFR useful for Müdigkeit?

The usefulness of MTHFR variants (e.g., C677T) for fatigue is not well supported by evidence. MTHFR encodes an enzyme in folate metabolism; certain variants can modestly raise homocysteine levels. However, a direct causal link to general fatigue has not been confirmed in high-quality studies. Fatigue has many causes (sleep deprivation, stress, iron deficiency, thyroid issues, psychological factors) that are far more common than an MTHFR polymorphism. Commercial DNA tests often overstate the impact. If elevated homocysteine is confirmed via blood test, supplementation with folate, B12, and B6 may be beneficial – but not based on genotype alone. Without lab values, the relevance remains unclear. Evidence is moderate (observational studies, GWAS) but insufficient for a clinical recommendation for fatigue. Caution: high-dose folic acid can mask B12 deficiency.