Recent Advances in the Interaction Mechanisms and Health Effects of Tea Polyphenols with Gut Microbiota

Tea polyphenols, such as catechins from green tea and theabrownins from dark tea, are able to produce multiple beneficial influences on human bodies, for instance antioxidant, anti‑inflammatory and metabolic‑regulating functions, but human bodies can barely take in these compounds after oral consumption. Most polyphenol compounds will arrive at the colon, where they carry out mutual interactions with gut microbes. Gut microbes can decompose tea polyphenols and convertthem into small‑moleculemetabolites including phenyl‑γ‑valerolactone, phenolic acids and short‑chain fatty acids (SCFAs), so human bodies can absorb and utilise these transformed substances more readily, and these metabolites also show relatively higher biological activity.At the same time, tea polyphenols can modulate gut microbiota homeostas,which promote the reproduction of beneficial bacteria, boost the production of short‑chain fatty acids, repair impaired intestinal barrier structures and regulate local intestinal immune responses. Different tea processing procedures will alter polyphenol compositions, which leads to varied modulatory effects on gut microbes.Even though plenty of findings have been obtained from animal and in‑vitro experiments, researchers still meet many obstacles when translating these findings into human clinical use, such as the absence of unified dosage‑effect standards, ambiguous mechanisms behind individual differences and unclear detailed molecular interaction patterns. This review summarises the intestinal metabolic process of tea polyphenols as well as their major ways to regulate gut microbiota, and it can provide certain references for subsequent research on precise nutrition and metabolic disease intervention.