Tea and human health: biomedical functions of tea active components and current issues

Chen et al. / J Zhejiang Univ-Sci B (Biomed & Biotechnol) 1673-1581 tea active components and current issues* Review: Zong-mao CHEN Zhi LIN Originating in China, tea and tea planting have spread throughout the world since the middle of the Tang dynasty. Now people from 160 countries in the world are accustomed to tea drinking. A brief history of tea's medicinal role in China and its spread to the world are introduced. The effectiveness of tea active components and tea drinking on major human diseases, including cancer, metabolic syndrome, cardiovascular disease, and neurodegenerative diseases, is discussed. Also presented are some related issues, such as the bioavailability of tea active components, the new formulations of tea polyphenols, and the safety for consumers of dietary supplements containing tea polyphenols. Tea; Cancer; Metabolic syndrome; Cardiovascular disease; Neurodegenerative disease; Bioavailability doi; 10; 1631/jzus; B1500001 Document code; A CLC number; Q946; 8 - After water, tea is the most frequently consumed beverage worldwide. It is well known that the tea plant originated from the southwest of China. As early as 40005000 years ago, the Chinese people had become aware that tea could promote health and prevent some human diseases. This was recorded in ancient books on medicine, like Shen Nongs Herbal Classic. The planted acreage of the tea plant was small before A.D. 581 but expanded rapidly during the period of A.D. 581618. It was recorded that the tea plant had then become a major crop in the southern part of China with vast plantation acreage. During the about 300 years of the Tang dynasty (A.D. 618907), the tea industry underwent rapid development, which may be closely related to the healthpromoting effects of tea. Works on tea were published in this period, such as Tea Classic, which was written by Yu LU of the Tang dynasty and is the earliest book on tea in the world. Even though the description of tea as a health-promoting and disease-preventing agent was found far before the Tang dynasty, the publication of Tea Classic greatly elevated the status of tea, and the imperial government even started to levy tea taxes to help replenish the state treasury. It was recorded that tea taxes collected during the reign of Tang Taizong (A.D. 627649) amounted to around 400 million fen (wen) (Mair and Hoh, 2009). There is an oft-quoted phrase that The tea industry in China was developed in the Tang dynasty and flourished in the Song dynasty. According to the historical record, the planting of tea was so widespread in the southern part of China during the Song dynasty (A.D. 9601279) that its distribution reached about three fourths of the territory of China in the twelfth century, indicating the popularity of tea consumption during that period. Tea had become a necessity of life for all citizens, from high officials, the intelligentsia, and down to the common people. Many new varieties of tea appeared in the Ming and Qing dynasties. The monumental medical monograph, The Compendium of Materia Medica, was completed by the famous medical and pharmacological scientist Shi-zhen LI in 1578 in the Ming dynasty. In total, 1892 mineral, botanical, and animal-origin medicines were recorded in this monograph, where tea was described as tea, bitter and cold in nature, capable of lowering excessive internal heat. From then on, the understanding that tea is beneficial to human health has been well recognized not only in China but also around the world. The spread of tea from China to the world dates back to the Tang dynasty mainly via the following three routes: (1) to Japan and Korea toward the east; (2) to Mongolia, Middle East, and Iran toward the northwest through land route, and further westward to Russia and other Slav countries; and (3) from Macau first to Holland through the sea route, then to France, Portugal, UK, and other European countries, and further to other countries including India, Ceylon (Sri Lanka), and African countries (Mair and Hoh, 2009). These routes, in consequence, created the history of tea planting and the custom of tea drinking in many countries in the world. Today, tea is planted in 60 countries, and people from more than 160 countries have formed the habit of tea drinking. The acceptance of and affection for tea by people from different countries and different ethnic groups are by and largely related to its beneficial effects on health. The development of tea from a traditional Chinese medicine to a modern medicine started in the 1980s. In a general spirit of returning to nature, there sprang up a wealth of research on the effective components of tea that might prevent or control many important diseases. Research came from more than 20 countries and regions including China, USA, UK, France, Germany, Japan, India, Israel, Italy, the Netherlands, South Korea, Australia, Canada, etc. According to the database of ISI Web of Knowledge (Thomson Reuters), more than 800 paper (...truncated)