What to watch with VDR and Müdigkeit?

VDR (Vitamin D receptor) variants are often marketed in connection with fatigue, but the evidence is limited. VDR SNPs (e.g., rs2228570, rs1544410) can modestly affect vitamin D metabolism and receptor function. Observational studies link low vitamin D levels to fatigue, but direct genotype–fatigue associations are inconsistent and not clinically actionable. Consumer DNA tests may report 'increased risk' for vitamin D insufficiency, but a blood test for 25-hydroxyvitamin D is far more reliable. Fatigue has many causes (anemia, thyroid, sleep disorders, stress) that should be evaluated by a physician. In Germany, the GenDG requires medical counseling for health-related genetic tests. Be skeptical of claims that a single VDR variant explains chronic tiredness. Evidence is mechanistic/unclear; no strong RCTs support genotype-based supplementation.