This randomized, double-blind, controlled clinical trial will evaluate the effects of daily cocoa flavanol supplementation on vascular and inflammatory biomarkers in healthy adult men aged 30 to 75 years. Participants will be randomized to receive either a cocoa flavanol supplement or a nutrient-matched low-flavanol control product for 4 to 8 weeks. The study will assess changes in inflammatory biomarkers, endothelial function, oxidative stress markers, vascular measurements, and circulating endothelial progenitor cell-related markers. Optional assessments include flow-mediated dilation and single-cell RNA sequencing of peripheral blood mononuclear cells to explore mechanistic biological responses to cocoa flavanol supplementation.