What role does B12 play in Müdigkeit?

Vitamin B12 (cobalamin) is essential for red blood cell formation, DNA synthesis, and neurological function. Deficiency can cause megaloblastic anemia and nerve damage, leading to fatigue, weakness, and cognitive impairment. The evidence linking B12 deficiency to fatigue is strong (human-moderate) when deficiency is confirmed. However, supplementing B12 in individuals with normal levels does not reliably reduce fatigue; many such claims are based on marketing rather than solid science. Blood tests (e.g., holotranscobalamin) can accurately diagnose deficiency. For persistent fatigue, other causes like iron deficiency, thyroid disorders, or sleep issues should be investigated. Genetic variants (e.g., in VDR) have minimal impact on B12 status. In summary, B12 plays a key role in fatigue only when deficient; otherwise, its effect is overstated.