Health Benefits of Green Tea and its Polyphenols: A Review

Tea is one of the most widely consumed beverages worldwide next only to water for enjoyment and health, and is available in various forms. Amongst all types of tea, Green tea is a popular drink, especially in Asian countries, although its popularity continues to spread across the globe. Various studies have been conducted since many years to understand the health benefits of Green tea which is derived from the leaves of the Camellia sinensis plant. Green tea is composed of polyphenols, caffeine, minerals, and trace amounts of vitamins, amino acids, and carbohydrates. Green tea contains more catechins, than black tea. There are four main catechins (polyphenols) found in Green tea: (-)-epicatechin (EC), (-)-epicatechin-3-gallate (ECG), (-)-epigallocatechin (EGC) and (-)-epigallocatechin-3-gallate (EGCG). All of them are known to boost the immunity in humans. Amongst these ECG, EGC, and EGCG have been shown to have antimicrobial action against a variety of microbes. Catechins are in vitro and in vivo strong antioxidants. In addition, the minerals and vitamins increase the antioxidant potential of this type of tea. Since ancient times, the traditional Chinese medicine has considered Green tea as a healthy beverage. It is known that the polyphenols present in Green tea stimulate the central nervous system and maintain overall health in humans. Much research is available depicting the health benefits of Green tea for a wide variety of implications, including different types of disorders. The current paper reviews such health benefits with a focus on its polyphenols.