Evidence check: Folsäure in the context of Müdigkeit

The provided context does not contain specific data on MTHFR variants and their link to fatigue or on folic acid versus methylfolate supplementation. MTHFR polymorphisms (e.g., C677T) are common and may impair conversion of folic acid to its active form (5-MTHF). However, evidence that methylfolate supplementation reduces fatigue in carriers is weak and inconsistent; many studies show no clinically meaningful benefit, especially when no folate deficiency exists. Direct-to-consumer tests like MyBody-X often provide oversimplified interpretations not supported by robust clinical trials. Uncritical use of methylfolate also carries risks (e.g., masking B12 deficiency). Therefore, a medical workup for fatigue and measured folate/B12 status should precede any supplementation. The overall evidence is unclear.