PROJECT SUMMARY/ABSTRACT Recent advances in high-throughput metabolomic studies have shown promise in elucidating potential pathways underpinning aging processes and longevity. However, data in human populations are still constrained by small sample sizes and a limited number of metabolites profiled. Existing studies have also not integrated data on diet and lifestyle to evaluate the associations of interest in a comprehensive manner. A better understanding of aging- related metabolic alterations and whether metabolite profiles are modulated by lifestyle factors is crucial to develop effective strategies to promote health and well-being. The main goal is to identify novel metabolite profiles associated with mortality and prolonged longevity, and investigate whether the metabolomic signatures of lifestyle factors are associated with mortality and longevity. We propose to leverage unique resources from two large U.S. cohorts with long follow-up and extended lifespan data: the Nurses’ Health Study (NHS) and the Health Professionals Follow-Up Study (HPFS) (n~8,100). The results will be replicated in two independent populations: the Women’s Health Initiative (WHI) (n~2,300), and the Prevención con Dieta Mediterránea (PREDIMED) Study (n~3,000), a population at high cardiovascular risk in Spain. This research application is aimed at: (1) identifying plasma metabolomic profiles and networks associated with mortality and longevity; and, (2) identifying the metabolomic signatures of a healthy lifestyle score and examining its prospective association with mortality and longevity. The proposed project is built on the numerous strengths of existing cohort studies in U.S. and Mediterranean populations, and supporting results from the preliminary work conducted by our multi- disciplinary team. Findings from this study will provide insights into the underlying mechanisms of longevity and advance our understanding of how plasma metabolomics may mediate the associations between lifestyle factors and mortality risk. The proposed research will generate new knowledge that can directly inform specific lifestyle interventions applicable in clinical settings to improve the health and well-being of adults as they age. The proposed research will provide a wealth of preliminary data to stimulate further research on longevity and healthy aging.