Green Tea is produced by heating the leaves shortly after harvesting through a process of steaming or pan-firing to prevent oxidation from occurring, and then rolling and drying the leaves. Black and Oolong Tea undergo full or partial oxidation, which makes the leaves–and subsequent brew—darker in color.
Some review articles have reported the relationship between the tea consumption and the human cancer risk. A general overview of the pertinent epidemiological studies on tea consumption and cancer prevention in different organs such as bladder and urinary tract, breast, colon and rectum, esophagus, kidney, liver, lung, pancreas, stomach, and uterus is provided.
The antioxidant property of tea is also associated with several other mechanisms e.g., depolarization of electrons, formation of intramolecular hydrogen bonds, rearrangement of the molecular structure. These compounds may also prevent oxidative reactions by chelating free copper and iron, which may catalyze the formation of reactive oxygen species in vitro.
Caffeine, 1,3,7-trimethylxanthine, is widely distributed in natural products, such as tea. Caffeine shows a variety of biological effects those have attracted the interest of pharmacologist and clinicians. Caffeine is regard as follows;
･ Diuretic
･ Cardiac muscle stimulant
･ Central nervous system stimulant
･ Smooth muscle relaxant
･ Elevates free fatty acids and glucose in plasma
In a prospective study of more than 74,000 subjects who were followed for 10 years, an inverse relationship was found between tea drinking and risk of stroke. During that time, 4,089 cases of stroke were recorded. After adjusting for other risk factors, tea consumption was associated with a significantly lower risk of stroke. Those who consumed four or more cups of tea per day had a 21 percent reduced risk of stroke compared to those who did not drink tea (Larsson SC, Virtamo J, Wolk A. Black tea consumption and risk of stroke in women and men. Ann Epidemiol. 2013 Mar;23(3):157-60).
The benefits of tea drinking
