Tea has a special component called caffeine. Caffeine acts as a stimulant. In other words it banishes drowsiness and clears the mind. It dispels melancholy and has from long ago been the source of tea's restorative power. Tea is given its flavour by a kind of protein called theanine. Perhaps what gives tea its sweetness or its deliciousness is the way that theanine stimulates the taste-buds. There is a lot of theanine in tea that comes from plants that have been covered, such as gyokuro (refined green tea) and matcha (powdered green tea).

The astringent taste of tea is due to tannin. Recently the components of tannin have been analysed in detail, and among these the one that has attracted most attention is catechin. Catechin has great medicinal qualities, for example, it suppresses cancer and is effective in the treatment of high blood pressure and heart disease. It also suppresses the influenza virus, and the propagation of the 0-157 virus. These properties have been confirmed medically.

The medicinal properties of tea, the power of caffeine to sooth the spirit, theanine's power to satisfy the sense of taste and catechin's maintenance of health, are drawing attention in modern society.