Tea, made from the Camellia sinensis plant, is one of the most widely consumed beverages in China and globally. Beyond its cultural significance, tea is rich in bioactive compounds such as polyphenols, polysaccharides, caffeine, and especially epigallocatechin gallate (EGCG), a potent antioxidant linked to numerous health benefits.
Prof. GAN Renyou, Assistant Professor in the Department of Food Science and Nutrition of The Hong Kong Polytechnic University, focuses his research on exploring how these compounds interact with the gut microbiota, which plays a vital role in breaking down tea components and enhancing their bioavailability and bioactivities. EGCG, for instance, is poorly absorbed in its original form. But colonic bacteria can convert it into more absorbable metabolites, amplifying its in vivo effects, supporting cardiovascular health and potentially preventing cancer.
Another key focus of Prof. GAN’s research is tea fermentation. The six main types of tea—green, yellow, white, oolong, black, and dark—undergo varying degrees of fermentation, each producing distinct chemical profiles. For instance, the unfermented green tea retains higher levels of catechins like EGCG, while the post-fermented dark tea yields theabrownins with unique ingredients that can fight against non-alcoholic fatty liver disease and obesity.
While regular tea consumption is linked to benefits such as improved cardiovascular health, better blood sugar regulation and cognitive support, Prof. GAN cautions against excessive use of concentrated green tea extracts, which may lead to adverse effects like liver damage. His work aims to identify safe and effective dosages, especially for use in supplements.
Tea’s expanding role in functional foods, beverages and even cosmetics, highlights its commercial and therapeutic values. Prof. GAN’s previous experience with patents further supports the development of tea-based bioactives for the health and wellness industries.
Although his findings are largely based on in vitro and animal studies, they lay a strong foundation for future clinical research. In China, where tea is both a daily ritual and a traditional remedy, his work bridges ancient practices with modern science - promoting tea as a powerful tool for preventive healthcare. Finally, tea can be considered as a typical example of “Food as Medicine”.
Source: PolyU Science Newsletter
https://www.polyu.edu.hk/fs/publication/e-newsletter/issue-6/interview---fsn/
