Potential Bioactive Components and Health Promotional Benefits of Tea ( Camellia sinensis )

Tea is prepared from the young leaves, buds, stalks of the plant Camellia sinensis. The cultivation process of tea plants and the habit of tea drinking were initiated in China from ancient times. Now, the consumption of tea is very popular throughout the world and it is an integral part of our social culture. Tea contains polyphenolic compounds (catechins and epicatechins), theaflavins, flavonol glycosides, L-theanine, caffeine, theobromine, and volatile organic substances. These bioactive components are responsible for the astringency, flavor, aroma, and taste of the tea as well as its health beneficial effects. Moreover, tea has several medicinal values. The phytochemical components are involved in the prevention and cure of many illnesses like cardiovascular diseases, malignancy, digestive dysfunction, and metabolic disorders like obesity, diabetes. Tea flavonoids show strong antioxidant properties. Caffeine and other methylxanthine regulate the intracellular second messenger levels. Additionally, catechins exhibit anti-inflammatory effects. All these multidimensional actions make some positive attributes in favor of neuroprotection, cardioprotection, and cancer prevention. Various approaches are also taken to use tea ingredients as an adjuvant in cancer therapy. This review emphasizes the importance of bioactive components, and their health promotional activities.KEY TEACHING POINTSOrigin and brief history of tea.Processing steps and characteristics of different types of teas. Bioactive components of teas (green and black tea), their biochemical characteristics and health promotional effects.Role of different bioactive components to control the various physiological and metabolic disorders.Possibilities of use of tea component in cancer therapy.