What role does Folsäure play in fatigue?

Folic acid (vitamin B9) is crucial for DNA synthesis, red blood cell formation, and homocysteine metabolism. A deficiency can lead to megaloblastic anemia, which commonly presents with fatigue, weakness, and pallor. However, deficiency is relatively rare in the general population due to dietary sources (leafy greens, legumes) and fortification in some countries. In non-deficient individuals, folic acid supplementation does not reliably reduce fatigue. Genetic variants, such as in the MTHFR gene, can impair the conversion of folic acid to its active form (5-MTHF), potentially affecting individual response. Evidence for a direct anti-fatigue effect in healthy people is moderate and largely observational. Clinical assessment should include serum folate, vitamin B12, and a complete blood count to rule out anemia. Caution: high-dose folic acid can mask vitamin B12 deficiency, especially in older adults. Therefore, supplementation should be guided by lab results and medical advice.