Health Benefits of Green Tea with Emphasis on Diabetes Mellitus

Abstract

Green tea (Camellia sinensis) is one of the most popular beverages in the world where about 3 Billon kg of tea are produced and consumed yearly. The chemical composition of green tea is very much complex and it contains higher amount of polyphenols (epicatechin, epicatechin gallate, eipgallocatechin and epigallocatechin gallate) as compared to black tea. The presence of this high amount of polyphenols in green tea makes it very important in the prevention of different diseases. So far green tea was shown to have many impacts in carbohydrate metabolism and it is considered as an alternative medicine for diabetes mellitus. Polyphenols in green tea reduce carbohydrate digestion and absorption in the intestine by inhibiting carbohydrate digesting enzymes and inhibiting glucose transporters across the intestine. They are also shown to increase secretion of insulin by pancreatic β cells and protect cytokine induced inflammatory damage of these cells. Increasing insulin activity and maintaining glucose homeostasis are other mechanisms by which green tea is involved in carbohydrate metabolism. In addition to its impact on carbohydrate metabolism green tea is known to have a preventive effect against cancer (of colon, esophagus, mouth, stomach, small intestine, kidney, pancreas, and mammary glands), bacterial, viral and fungal infections, cardiovascular diseases, lung injury, non-alcoholic fatty liver and neurodegenerative disorders. Even though the health benefit of green tea is high some dose dependant adverse effects may be observed. There is a need to conduct in depth human based studies to monitor pharmacological and clinical effects of green tea therefore people can be benefited from it as an alternative medicine.