Drinking tea is a worldwide habit, and the amount of tea consumed varies from one region to another. For example, more tea than coffee is consumed in the UK while the reverse is true with the USA. In India, the South consumes a lot of coffee, while in the North, tea is the preferred drink. There are several health benefits associated with tea. These include the cholesterol lowering effect and the anti mutagenic and therefore anti carcinogenic properties. Two major forms of tea are the black and the green varieties. Both are obtained from the same plant, but the two forms arise as result of differences in processing. Fermentation is involved in the preparation of the black tea which is not the case with the green tea.
Generally, the caffeine content of green tea is lesser than that of the black tea. So green tea is suitable for people who do not prefer caffeine. Caffeine is an alkaloid. Caffeine has been the object of much research worldwide. On the positive side, caffeine has the ability to stimulate the central nervous system. This in turn leads to increased alertness and elevated concentration levels. On the negative side, caffeine has been found to be addictive, and is capable of producing withdrawal symptoms. It can also stimulate acid secretion in the gastric region. The positive effects of caffeine are more when coffee is consumed in moderate amounts. When caffeine intake increases, it can produce depression, and very high concentrations can be toxic.
Black tea has a slightly higher caffeine concentration compared to green tea. The caffeine levels in black tea are slightly lower compared to coffee, but the amount in tea becomes even lower because more amount of coffee is used to prepare the beverage as compared to tea. The duration of brewing tea is ultimately reflected in the caffeine content of tea. The optimum time taken should be three minutes for optimum extraction and minimal caffeine content. As the extraction time crosses three minutes, the caffeine content and bitterness of the beverage increase. Tea in the dust form is widely used in India because it is cheaper and gives a darker color. Tea dust and tea in bags give higher caffeine content because of the smaller particle size. The caffeine extraction is less when tea is present in the leaf form.
The antioxidant content of both forms of tea is approximately about the same, but the antioxidant composition varies. In green tea, catechins are the major antioxidants, while in black tea thearubigins are the major free radical scavenging components. Both these classes of antioxidants have the same effect. Free radicals which are highly reactive components produced during cellular reactions, are capable of damaging cellular membrane, and vital biological molecules like the DNA. Damage to the DNA molecule is called mutation which in turn can result in carcinogenesis. Both coffee and tea contain antioxidants, but caffeine content of tea is lesser. Thus it is better to drink coffee in moderate amounts, while tea can be taken in larger quantities, preferably the green variety.