Polyphenols in Health and Disease: Gut Microbiota, Bioaccessibility, and Bioavailability

Polyphenolic compounds (PC) are among the most abundant secondary metabolites in nature. They are widely distributed in the world and can be found in fruits, cereals, tea, coffee, and beverages. Due to their structural diversity, polyphenols have many different properties and biological effects. They are resistant to the acid of the gastric tract, and very few are hydrolysed or absorbed in the stomach. Significant portions of ingested polyphenols reach the large intestine and interact with the local bacteria, the so-called gut microbiota. Epidemiological studies confirm that moderate and prolonged intake of foods rich in polyphenols could prevent the development of cancer and chronic diseases, such as cardiovascular, neurodegenerative, type 2 diabetes, and obesity. The current work aims to provide an updated overview on the nature and occurrence of polyphenols, quantification methods, bioaccessibility and bioavailability, and impact on human health, namely through interactions with the gut microbiota.