Is MTHFR useful for longevity?

Whether MTHFR is useful for longevity is a common question in personalized nutrition and direct-to-consumer DNA testing. MTHFR (methylenetetrahydrofolate reductase) is a key enzyme in folate metabolism, influencing homocysteine levels. The common C677T variant reduces enzyme activity. Elevated homocysteine is a risk factor for cardiovascular disease, which can impact lifespan. However, the direct effect on longevity is small and confounded by many other factors. Evidence comes mainly from association studies (human-moderate). Supplementation with active folate (5-MTHF) can lower homocysteine in carriers, but a clear benefit for extending lifespan is not proven. Many commercial tests overstate its importance. In summary, MTHFR is a useful marker within a comprehensive risk profile, but not a direct 'longevity gene'. Its clinical relevance is moderate and should not be interpreted in isolation.