Tea and health: a historical perspective.

In many parts of the world, green tea and black tea are produced from the plant Camellia sinensis. Tea is one of the most widely consumed beverages, second only to water. It is one of the safest beverages since it is made with boiling, sterile water and has been popular for over 4000 years. Dogma has it that people knew it might have health promoting properties since it was frequently used as fluid supply for patients suffering from infectious diseases. However, detailed, focused research on the health benefits of tea is of recent vintage. Initially, such research was carried out in Japan and China and, because the local customs, this research involved green tea. Now, a number of other scientists in Europe and in the United States have conducted investigations on black tea, and in some laboratories exacting comparative studies were performed utilizing black and green tea. The major interest in tea and health stems from the high level of antioxidant tea polyphenols in green tea and black tea. The chemistry of the tea polyphenols has been worked out to some extent. Thus, their role in lowering the risk of heart disease and of a number of types of cancer begins to be understood. Most productive are multi-disciplinary approaches, considering data from epidemiology and field studies, and laboratory research in animal models for heart disease and cancers of various types, as well as through in vitro experiments.