Fundamental and applied aspects of catechins from different sources: a review

Catechins belong to the group of flavonoids. Numerous studies show that consuming foods rich in catechins such as vegetables, fruits and especially teas may decrease the risk of developing various diseases. Therefore, we present in this compilation a critical and detailed analysis of the works published in the last 6 years and a guide for the reader with the main analytical techniques of quantification, in vitro and in vivo biological activities, the mechanisms of action in the organism and the bioaccessibility in treating the gastrointestinal effects of catechins from different matrices. The information presented in this review is important for a broad understanding of benefits that catechins can bring to human health and can be taken as an example for the study of new matrices, new effects and possible forms of application, such as dietary supplements or functional food ingredients for health promotion and the reduced risk for developing diseases.