Myths vs facts: CYP2D6 and Sport

CYP2D6 is a liver enzyme responsible for metabolizing many drugs and xenobiotics. In sports, myths claim that certain variants (e.g., 'ultra-rapid metabolizers') enhance performance or alter doping tests. The facts: CYP2D6 primarily affects the metabolism of opioid painkillers like codeine (a prodrug) and some beta-blockers. Ultra-rapid metabolism can lead to increased morphine formation – relevant for pain management, not direct performance enhancement. There is no robust evidence that CYP2D6 variants significantly improve endurance, strength, or recovery. Associations are mostly mechanistic or derived from pharmacogenetic studies, not from sports GWAS. MyBody-X tests for CYP2D6 may offer clues about drug tolerance, not athletic aptitude. Beware of overclaims: single-SNP 'sport gene' scores lack scientific validation. The evidence is mechanistic, not clinically validated for sports. For performance optimization, focus on training, nutrition, and medical advice – not genetic tests.