Bioactive Compounds in Coffee: Metabolism, Bioavailability and Health Effects—A Review

Coffee is a very popular psychoactive beverage with a complex composition. Besides its stimulant effect due to caffeine, it contains several bioactive compounds with antioxidant properties and potent metabolic activity. Its clinical efficacy is fundamentally determined by the bioavailability and metabolic fate of its constituents. The bioactive components of coffee, such as polyphenols, melanoidins, phytosterols, biogenic amines, and carotenoids, have notable antioxidant, anti-inflammatory, and immunomodulatory effects. This review aims to present the main bioactive components of coffee, their biological effects, mechanisms of action, and the influence of preparation methods and individual variability on metabolic outcomes in common chronic diseases. The data are synthesized from clinical, prospective, and interventional studies to examine how processing variables and biological metabolism influence the health-promoting potential of coffee antioxidants. Brewing methods like hot filtration optimize the extraction of these antioxidants. Individual clinical outcomes are further modulated by genetic polymorphisms and gut microbiota variability, which influence the activation of the cellular Nrf2 antioxidant defense pathway.