Polyphenols are products of secondary plant metabolism, widely used as biologically active compounds in pharmacology, medicine, and agriculture. These compounds are found in all organs of a wide variety of plants (fruits, seeds, roots, bark, wood, leaves). All plant polyphenols in relation to animal organisms, to one degree or another, have a wide range of biological activity, being an important part of the diet and are currently in the center of scientific attention. Various plant polyphenols are an essential component of any diet that includes plant foods, and their daily intake in a normal diet averages at least 1 g/day. The biological effects of plant polyphenols are diverse and specific, due to the diversity of their chemical structure. Studies have shown that diets rich in fruits and vegetables reduce the risk of developing a number of chronic diseases associated with systemic low-grade chronic inflammation, such as type 2 diabetes, atherosclerosis and cancer; a high level of consumption of fruits and vegetables is inversely proportional to the incidence of a number of degenerative diseases; antioxidant, anti-inflammatory, immunomodulatory, antihypertensive, neuroprotective, hepatoprotective effects of plant polyphenols have been confirmed; benefits have been shown in the rehabilitation and prevention of cardiovascular and neurovascular diseases.