welche vitamine helfen bei müdigkeit — which blood markers matter?

The question about which vitamins help with fatigue and which blood markers matter is clinically relevant but not straightforward. Fatigue is multifactorial; common nutritional deficiencies include vitamin B12, folate, vitamin D, and iron (not a vitamin but critical). Blood markers such as ferritin, vitamin B12, 25-hydroxyvitamin D, and TSH can indicate underlying issues. However, evidence for routine vitamin supplementation in non-deficient individuals is weak. Only when a deficiency is confirmed (e.g., B12 < 200 pg/mL, ferritin < 30 ng/mL) does supplementation show clear benefit. The provided context discusses DNA tests for diet and metabolism (e.g., APOA2, PPARGC1A) but does not directly address vitamins or fatigue. Therefore, the answer is conservative: blood markers can guide targeted testing, but self-diagnosis and supplementation without lab confirmation are not evidence-based. A medical workup is recommended.