Polyphenols constitute a diverse class of naturally occurring compounds found abundantly in plants, characterized by multiple phenol structural units. They are secondary metabolites that contribute to the color, flavor, and defense mechanisms of plants against pathogens and UV radiation. Common dietary sources include berries, apples, onions, tea, coffee, and red wine. Polyphenols exhibit strong antioxidant activity by scavenging free radicals and chelating metal ions. Research indicates potential benefits in reducing oxidative stress, inflammation, and risk of chronic diseases such as cardiovascular disease and certain cancers. However, bioavailability varies significantly among different polyphenols. They are generally stable under normal conditions but can degrade with prolonged heat or alkaline pH.