Evidence check: SHBG in the context of longevity

SHBG (sex hormone-binding globulin) is often discussed in the context of longevity, but the evidence is primarily observational. Higher SHBG levels are associated with better metabolic health and reduced all-cause mortality in some cohort studies. However, it remains unclear whether SHBG is a causal factor or merely a marker of underlying health status such as insulin sensitivity, liver function, and body composition. Genetic variants in the SHBG gene (e.g., rs1799941) have modest effects on circulating levels. A single SHBG measurement cannot predict individual longevity. Lifestyle factors—diet, exercise, weight management—have a far greater impact on SHBG and health outcomes. Be cautious of commercial tests that overstate SHBG as a 'longevity biomarker.' The evidence does not support clinical use for longevity prediction.