The Tea Plant - Camellia sinensis (L.)0. KUNTZE

Author(s): Bertram, B.

Abstract: The worldwide consumption of tea as a beverage is second only to that of water. Tea is obtained from young leaves and buds of Camellia sinensis (L.) 0. KUNTZE, indigenous to mountainous regions of Southeast Asia and cultivated in East Asia for more than 2000 years. Green tea is manufactured by rapid heating followed by drying of freshly harvested leaves. Fermentation of the withered, rolled and crushed fresh leaves at high humidity gives black tea. Besides caffeine, which is present in both tea qualities, green tea contains high quantities of flavanols (catechins), flavonol glycosides, small amounts of condensed and hydrolysable tannins, and saponins. Tannin related, coloured oxidation products of flavanols, particularly the poorly characterized thearubigens, prevail in black tea, which also contains theaflavins, small amounts of theaflagallins and bisflavanols (theasinensins), and unchanged flavonol glycosides. In both tea qualities, unusually high levels of fluorides and of Aluminium are found.Consumption of green and black tea has been reported to be beneficial to human health. Many laboratory studies have demonstrated inhibitory effects of tea preparations and tea polyphenols against tumor formation and growth, and there is some evidence from epidemiologic studies, that tea may have a protective effect on certain cancers. This effect is believed to be mainly due to antioxidative properties of the tea polyphenols, coupled with their ability to inhibit carcinogen activating enzymes and to suppress endogenous formation of N-nitroso compounds. In addition, virostatic, bacteristatic and reverse-transcriptase-Inhibitive, as well as antiatherosclerotic effects are reported. Green tea extracts and flavanols decrease blood pressure, plasma glucose and cholesterol levels in vivo, inhibit platelet aggregation in vitro, and seem to lower the risk of coronary heart disease.

Keyword(s): Green Tea

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