How are HDL and longevity related?

HDL (high-density lipoprotein) is commonly called 'good cholesterol' because epidemiological studies show higher HDL levels are associated with lower cardiovascular risk, which indirectly supports longevity. However, causality is uncertain: Mendelian randomization studies found no evidence that genetically elevated HDL protects against heart attack. Moreover, recent data suggest a U-shaped relationship – very high HDL (>80 mg/dL in men) may even increase mortality. Thus HDL is not an independent longevity marker but rather a proxy for a healthy lifestyle (exercise, moderate diet, non-smoking). A DNA test or single blood test alone cannot predict individual lifespan. The evidence is moderate, based on observational studies; for personal assessment, consult a physician and consider additional biomarkers (LDL, triglycerides, inflammation).