Evidence check: CYP2C19 in the context of Sport

CYP2C19 is a cytochrome P450 enzyme primarily involved in drug metabolism, notably for clopidogrel and proton pump inhibitors. In the context of sport, there is no strong evidence that common CYP2C19 variants directly affect athletic performance, recovery, or injury risk. Some research explores links to caffeine metabolism or painkiller response, but effect sizes are small and not clinically actionable for athletes. Direct-to-consumer tests that claim CYP2C19 can guide sports nutrition or training are largely marketing-driven. The evidence level is 'mechanistic/unclear'. Important caveat: CYP2C19 status does have validated relevance for clopidogrel efficacy (a medical drug), but this is unrelated to sport performance. Do not change supplement or medication regimens based solely on this genetic information without consulting a physician.