The Health Benefits of Tea
~ September 1997 No.15 ~
The drinking of tea stretches back into ancient times. It can easily be traced back over 5000 years in China, but it probably has been consumed in that country for even longer. As long as people have been drinking tea, there have been stories of its benefits to health. This warm beverage is a good source of caffeine. As well as caffeine, tea contains a wide variety of compounds that may be good for everything from your teeth to your cardiovascular health.
It is the polyphenols in tea that are being touted as the main compounds responsible for the possible beneficial effects of tea on cancer and cardiovascular disease. Why the polyphenols? Their chemical structures give polyphenols potent antioxidant properties. Antioxidants are able to neutralize the very damaging effects of oxygen molecules and free radicals that are present in the body. Free radicals are very powerful oxidants which means that they can damage cells in the body. Oxygen can similarly cause cell damage in the body. Over time this damage may lead to cancer or to cardiovascular disease.
Polyphenols are chemical compounds with molecular weights generally greater than 500, that are often referred to as tannins. It is the tannins that give tea the slight astringent taste, especially when it is brewed strong. Close to forty percent of a green tea leaf is polyphenols (on a dry weight basis). A search of the scientific literatures reveals a long list of tea polyphenols that have been extracted and identified. The most important polyphenols to be found in tea are the flavan-3-ols also known as catechins and the flavonols. The chemical structure of these compounds are complex, consisting of several benzene rings. It is this chemical structure that gives these compounds their antioxidant properties.
The task of extracting, purifying and identifying the various compounds in tea is a long and difficult process. However, it seems that the more scientists know about what is in tea, the more they are convinced that the Chinese may have been right all along when it comes to the health benefits of tea.
|Botanical name:||Camellia sinensis|
|Calories in a cup of tea:||2|
|Types of tea:||green, black and Oolong|
|Differences between types of tea:||the way they are processed after harvest|
|Caffeine content in a cup of tea:||34 mg / 170 ml|
|Caffeine in a cup of coffee:||99 mg / 170 ml|