ABSTRACT
Tea is one of the most popular beverages in the world. Drinking a cup of tea for pleasure or in times of stress is a part of daily life for millions of people all over the world. It is estimated that one-half of the population in the world consumes tea. The production and trade of tea has become an important business for centuries. In 1990, the tea growing area in the world reached 2.45 million hectares and total output reached 2.51 million tons. World tea consumption has increased steadily. China, for example, has experienced an increase in tea consumption of 6.0% annually for the period 1961-1984 and is expected to maintain the momentum at a rate of 10% to the year 2000. In the United Kingdom, annual tea consumption is expected to increase 1.4% annually until the year 2000. In terms of annual tea consumption per capita, Ireland has the highest value at 3.07 kg (triennial average over the period 19861988), followed by Iraq (2.95 kg), Qatar (2.91 kg), UK (2.84 kg) and Turkey (2.73 kg) for the same period (Robinson and Owuor, 1992; Chen and Yu, 1994). The daily consumption of tea is approximately 3 billion cups all over the world. About 80% of consumers prefer black tea and the rest consume green tea and semi-fermented oolong tea. Green tea is preferred in China, Japan, and Middle East countries, the oolong tea is mainly consumed in the eastern part of China and in Japan. In Great Britain, tea is drunk by more than 80% of the population. The average intake for those tea drinkers considering tea as a healthy drink was estimated to be 0.8 litre per day (Marks, 1992). Tea is effective for quenching thirst. However, the ability of tea to quench thirst is not the main reason for its popularity as a beverage. This relies much more on its sensory properties, customs, prices, availability and apparent health benefits. Because of the high popularity of tea, the relationship between tea and health has come as one of the most attractive topics in biomedical sciences.
