DHEA-S, or Dehydroepiandrosterone Sulfate, is a biomarker commonly used in longevity research. It is a sulfated version of the hormone DHEA, which is produced by the adrenal glands. DHEA-S levels decline with age, and some studies have suggested that higher levels of DHEA-S are associated with better health and potentially longer lifespan. However, more research is needed to fully understand the role of DHEA-S in longevity. As a biomarker, DHEA-S can provide valuable insight into the aging process and may hold potential for future interventions to promote healthy aging.