Antioxidant and anti-inflammatory roles of tea polyphenols in inflammatory bowel diseases

Polyphenols, including phenolic acids, flavonoids, and procyanidins, are abundant in food and beverage derived from plants. Tea (Camellia sinensis) is particularly rich in polyphenols (e.g., catechins, theaflavins, thearubigins, gallic acid, and flavonols), which are thought to contribute to the health benefits of tea. High intake of tea polyphenols has been described to prevent and/or attenuate a variety of chronic pathological conditions like cardiovascular diseases, neurodegenerative diseases, diabetes, and cancer. This review focuses on established antioxidant and anti-inflammatory properties of tea polyphenols and underlying mechanisms of their involvement in inflammatory bowel diseases (IBD). Tea polyphenols act as efficient antioxidants by inducing an endogenous antioxidant defense system and maintaining intracellular redox homeostasis. Tea polyphenols also regulate signaling pathways such as nuclear factor-κB, activator protein 1, signal transducer and activator of transcriptions, and nuclear factor E2-related factor 2, which are associated with IBD development. Accumulating pieces of evidence have indicated that tea polyphenols enhance epithelial barrier function and improve gut microbial dysbiosis, contributing to the management of inflammatory colitis. Therefore, this study suggests that supplementation of tea polyphenols could prevent inflammatory conditions and improve the outcome of patients with IBD.