12. Strong Evidence for Slowed Aging in Humans Must Show Durable, Multilevel Benefit

Strong evidence would require convergent changes: slowed increase of validated multi-system biomarkers, delayed onset/accumulation of multiple age-related conditions, and preserved or improved functional capacity over time, ideally in randomized settings. Single-disease prevention is not sufficient; the hallmark would be a broad shift in multi-morbidity and resilience trajectories. Because humans are already highly protected, effects from genetic, dietary, pharmacological, and lifestyle factors are expected to be modest and require sensitive, systems-level endpoints.