Baldi, A; Abramovič, H; Poklar Ulrih, N; Daglia, M; ,
Tea, a water infusion of leaves from Camellia sinensis (L.) Kuntze, is the oldest, most consumed beverage worldwide. Archeologists have recently discovered traces of tea drinking dating to around 206 B.C. There are five major types of tea, differing in production processes and, therefore, in chemical composition: green tea, white and yellow teas, oolong tea, black tea, and dark tea. Compounds identified in green tea are involved in several biological activities and can have various health-promoting functions, which can include antioxidant, anti-inflammatory, antiviral, anticancer, antidiabetic, and anti-obesity activities, as well as activities against CVD and neurodegenerative diseases, and many others. These beneficial effects are mainly ascribed to tea catechins, bioactive constituents belonging to the flavonoid family (flavan-3-ols subclass), which represent approximately 70% of all polyphenols in tea. However, the maximal concentrations of the catechins detected in blood in human subjects or animals after oral ingestion are in submicromolar or low micromolar levels, which indicate that only small amounts are absorbed and passed into the blood. Chapter “Tea Catechins” describes the chemical composition of C. sinensis leaves and the beneficial effects on human health upon tea consumption, focusing on tea catechin bioactive constituents. This chapter also takes into account their bioavailability, toxicological aspects, and safety profiles. Furthermore, recent applications of tea catechins in the food market are presented.