How are Folsäure and fatigue related?

The relationship between folic acid and fatigue is primarily mediated through folate metabolism and red blood cell production. Folate deficiency can cause megaloblastic anemia, which typically presents with fatigue, weakness, and poor concentration. Additionally, folate is involved in homocysteine regulation; elevated homocysteine levels are associated with cardiovascular and neurological symptoms that may contribute to fatigue. Genetic variants such as MTHFR C677T affect the conversion of folic acid to its active form (5-methyltetrahydrofolate) and can modulate individual susceptibility to fatigue when intake is insufficient. However, the evidence is largely mechanistic: most studies show a link only in the presence of deficiency, not in adequately nourished individuals. Direct-to-consumer DNA tests that claim to predict a 'fatigue predisposition' via folate-related SNPs often overstate effect sizes. A balanced diet rich in folate (kale, legumes, liver) or targeted supplementation (e.g., during pregnancy) is reasonable, but a general causal link without clinical deficiency is not established. Caveat: fatigue has many causes – iron deficiency, sleep disorders, stress – and should be evaluated medically.