Tea drinking is associated with improved health. In particular, those who drink tea may reduce their risk of developing certain cancers (particularly of the gut), cardiovascular disease, dementia and obesity. The reason for the health effects of tea likely relates to the high concentrations of antioxidant phytochemicals it contains. However, not all tea is the same, and different types of tea have very different chemical compositions.
Camellia sinensis
All tea is made from the tea plant Camellia sinensis. The plant is grown in India and China as well as other Asian countries, and varieties differ depending on the region of growth. The Camellia sinensis plant is a rich source of catechin antioxidants, polyphenols belonging to the flavonoid class of phytochemicals. These antioxidants are thought to confer particular health benefits to man, although other components such as L-theanine also contribute significantly.
Black Tea
Black tea was created by the tea companies because shelf life is improved and this allowed the export of tea via long sea journeys. Black tea is formed by fermenting the leaves of the tea pant. This process allows the oxidation of the parent catechin molecules into theaflavin and thearubigin molecules through the action of polyphenol oxidase. Theaflavins and thearubigins give black tea its characteristic taste and colour.
Green Tea
Green tea is made by steaming the leaves of the Camellia sinensis plant to deactivate the enzyme polyphenol oxidase. Because polyphenol oxidase is responsible for the breakdown of polyphenols to theaflavins and thearubigins, green tea maintains the high concentrations of catechins found in the parent plant material. Catechins are more potent antioxidants than either theaflavins or thearubigins and this may explain the greater health benefits of green tea.
Darjeeling Tea
Darjeeling tea is classified as a black tea that originates from the Darjeeling region of India. Although classified as a black tea because it has been through a fermentation process, the final product is actually only around 90 % fermented. This give it a much lighter greener colour than regular black tea as the concentrations of theflavins and thearubigins are lower. Darjeeling therefore has the highest catechin content of any black tea.
Which Tea To Drink?
The caffeine content of most teas is similar. But the levels of other phytochemicals in the tea tends to vary. Because the health benefits of the various components of tea are not fully understood, it makes sense to drink a variety of teas to ensure intakes of all the possible beneficial chemicals. Because Darjeeling tea contains the theaflavins and thearubigins of black tea as well as the catechins of green tea, drinking it regularly might confer the benefits of both types of tea.
RdB