welche vitamine fehlen bei müdigkeit — which blood markers matter?

Fatigue can stem from various nutrient deficiencies. Key blood markers include ferritin (iron stores), vitamin D, vitamin B12, folate, and TSH (thyroid function). A complete blood count (CBC) can reveal anemia. Iron deficiency is a well-established cause of fatigue, especially in menstruating women. Vitamin D deficiency is linked to tiredness, but evidence is moderate – randomized trials show small effects. B12 and folate deficiencies can cause megaloblastic anemia and neurological symptoms. Crucially, DNA tests (e.g., MTHFR variants) are not substitutes for direct blood measurements. Single-gene effects are small and not clinically actionable. Always consult a doctor for interpretation before supplementing. MyBody-X offers screening-level tests, but confirmatory lab work is needed. Evidence: human-strong for iron and B12, human-moderate for vitamin D. Caveat: fatigue is multifactorial – sleep, stress, thyroid, and inflammation (CRP) also matter.