Antioxidant activity is strongly influenced by the amount of total phenolics, natural habitat and the specific growing conditions (climate, soil minerals, humidity external contaminants), flowering period and other factors. A number of degenerative diseases i.e. cancer, autoimmune diseases, rheumatoid arthritis, cardiovascular etc. are due to oxidative stress. The human body has several mechanisms to counteract oxidative stress, by producing natural antioxidants or by submitting them to the outside through food and/or supplements. Once the antioxidant enters the body, it does not necessarily pass unchanged through the gastro-intestinal tract. It must therefore be considered bioavailability and bioactivity. The bioavailability of phenolic and polyphenolic compounds was studied in detail over the past two decades, whether by examining the kinetic models of polyphenol absorption in body fluids of healthy free radicals or by enhancing the immune system and reducing the risk of cancer and degenerative diseases. In recent years, there has been an increased interest in finding natural antioxidants because they can interfere with the distribution of reactions of free radicals. The most effective components are phenolic compounds contained in many vegetable raw materials.