To the big group of flavonoids (Plant dyes) counting Phenol compound (Polyphenol). It occurs in plants such as in various types of vegetables and fruits, in chocolate, in green tea as well as in the berry shells, stems and grape seeds of mainly red wines. For example, Merlot and Pinot Noir have a high proportion, while Syrah has a low proportion. Catechin plays as a defense against microorganisms an important role and is for example in infestation by real mildew formed spontaneously as a defense reaction. Such substances are called phytoalexins designated. Catechin contributes to the formation of tannins at or is a part of it. It is one of the tannins and practices in wine astringent Effect on. But above all it is for the bitter Taste responsible. The substance has an antioxidant and therefore has a health benefits, positive effect on increased blood fat.