Polyphenols are a large family of naturally occurring phenols that are abundant in plants and structurally diverse. They are micronutrients that naturally occur in plant foods, such as fruits, vegetables, herbs, spices, tea, dark chocolate, and wine. Polyphenols are not well-defined, but it is generally agreed that they are natural products "having a polyphenol structure (i.e., several hydroxyl groups on aromatic rings)" including four principal classes: "phenolic acids, flavonoids, stilbenes, and lignans". There are more than 8,000 types of polyphenols that have been identified so far. Some of the best-known sources of polyphenols include red wine, dark chocolate, tea, and berries. Polyphenols are powerful antioxidants, meaning they can neutralize harmful free radicals that would otherwise damage your cells and increase your risk of conditions like cancer, diabetes, and heart disease. They are also thought to reduce inflammation, which is thought to be the root cause of many chronic illnesses. Polyphenols have many other health benefits, and some studies strongly suggest that diets rich in polyphenols may offer protection against the development of certain cancers, cardiovascular diseases, diabetes, and neurodegenerative diseases.