welche supplements brauche ich test — what symptoms are typical?

The question 'which supplements do I need?' is popular but scientifically challenging. Tests that recommend supplements based on DNA variants (e.g., MTHFR, VDR, GST) typically rely on mechanistic associations or GWAS with small effect sizes. Typical symptoms that lead people to such tests include fatigue, brain fog, hair loss, brittle nails, or vague digestive issues – all non-specific signs that can have many causes. A blood test measuring actual levels (e.g., vitamin D, ferritin, B12) is far more informative than a DNA-only test. Evidence for personalized supplementation solely from genetic markers is weak; most recommendations are based on population averages or expert opinion. Moreover, supplements can cause harm when overdosed (e.g., fat-soluble vitamins, selenium). Bottom line: No test replaces a medical workup for genuine deficiency symptoms. The listed symptoms are not specific to supplement needs.