Project Abstract / Summary Our broad goal is to reduce the consequences caused by premature aging through addressing key research gaps that represent challenges to more effective mitigation efforts, particularly in low- and middle-income countries. Our central working hypothesis is that optimal early-life nutrition reduces physiologic aging, specifically via persistent impacts on DNA-related mechanisms (DNA methylation [DNAm], telomere length) over the human life course. The rationale extends key previous findings from the study team, particularly that (1) gestational exposure to the Dutch famine resulted in observable epigenetic differences in adulthood; (2) telomere length of infants and children differ by early-life maternal factors and metabolic indicators; and (3) exposure to a nutrition supplementation intervention led to reduced diabetes incidence at age 37-52 y. We have been following a unique cohort of individuals who participated as children in a nutrition supplementation intervention trial conducted in four villages in Guatemala from 1969 to 1977. We define full intervention exposure as the first 1,000 days of life between conception and two years of age; participants with full exposure will be compared to those with partial (0-999 of these ‘first 1,000 days’) and no intervention exposure. In this study, we propose to extract DNA from frozen buffy coats collected between 2015-2017 from these now-adult cohort participants (n=1,139). We will assay samples for DNAm and leukocyte telomere length, which are two mammalian aging hallmarks. In Aim 1, we will evaluate the impact of nutrition supplementation during the first 1,000 days on DNAm patterns and DNAm- calculated epigenetic age, including PhenoAge and other epigenetic clocks. We will also further examine CpG sites associated with early-life nutrition exposure with Mendelian randomization to assess causal associations with diabetes or BMI. In Aim 2, we will determine whether (1) nutrition supplementation during the first 1,000 days, and (2) life course nutritional status trajectories are associated with longer leukocyte telomere length. This innovative study will be an opportunity to examine the effectiveness of an actionable early-life nutrition intervention on the human health span. It will be the first epigenome-wide association study utilizing Mendelian randomization to assess early-life nutrition supplementation and adult metabolic outcomes to our knowledge. If successful, this study has the potential to identify novel subclinical physiologic aging indices that are nutrition- sensitive, which could lead to better intervention impact assessment and prevention strategies for premature aging. This innovative, multidisciplinary study is optimally suited to answer profound questions relating to early- life determinants of the human health span in adulthood. It builds upon extensive (>50y) and productive (>300 published papers) experience with this cohort, and a successful history of col...