welche supplements brauche ich test — what does this mean exactly?

The question 'which supplements do I need test' refers to commercial tests that claim to provide personalized supplement recommendations based on DNA variants, blood markers, or microbiome data. Such tests are often marketing-driven and rely on weak evidence. While certain gene variants (e.g., in FADS1, MTHFR, or VDR) can modestly influence nutrient needs, the effects are small and usually compensated by diet. There is no established 'supplement requirement test' in evidence-based medicine. More reliable is targeted diagnostic testing when a deficiency is clinically suspected (e.g., vitamin D, B12, iron) via blood analysis. Consumer DNA tests do not provide a sound basis for supplement dosing. Risks include overinterpretation, unnecessary expense, and potential side effects from unmonitored intake. My advice: Do not take supplements based solely on such tests; instead, seek medical guidance and prioritize a balanced diet.