Tea polyphenols is the name collectively refers to the polyphenol of tea leaves, including flavanols (flavan-3-ols), anthocyanins, flavonoids, flavonols and other phenolic acids. Among them, flavanols (catechins) is most important.

Tea polyphenols, also known as tea tannin, is one of the main ingredients of tea color, flavor formation, but also one of the main ingredients in tea health functions. Tea polyphenols and other active substances possess detoxifying and anti-radiation effect and can effectively prevent radioactive substances invading the bone marrow, and strontium-90 and cobalt-60 can be rapidly excreted. It is hailed as "radiation nemesis".

Green tea may protect against cardiovascular disease and disorders of the liver. [2]
 

Tea is high in fluoride. Drinking too much tea, especially in areas that use a lot of brick tea have high incidences of fluorosis as in Tibet, China.[1]