Tea, next to water, is the most widely consumed beverage in the world, consumed by both the privileged and the masses. Treatises on the historical, technical, botanical, pharmacological and medical aspects of tea have appeared regularly starting with Lu Yu's Ch'aChing, or "Tea Script," published in 780 A.D.
19th century cartoon linking tea and health
when plumpness was considered healthy 
The adulteration of green tea became profitable during the seventeenth century. It drew widespread concern as did fears of many kinds of food adulteration in an era in which chemistry was beginning to play a role in detecting fraudulent goods. [Accum, Phil. 1820; Smith, London 1827]
Throughout the centuries, the practice of boiling water to make tea has probably saved millions of lives during epidemics of cholera, typhoid fever, and others caused by waterborne pathogens. [Jacob Bigelow (Boston 1854); Sigmond (London, 1839)] Before World War II, the major producers of green and oolong tea were China and Japan. Americans consumed 40% green tea, 20% oolong and 40% black tea. During World War II, tea from China and Japan was not available, but trade routes to India, which produced only black tea, remained open. After World War II, most of the tea consumed in the U.S. was black. In recent years, with revelations about its health benefits, sales of green tea have grown. In the 1950s, scientists were convinced that tea had beneficial qualities, but their convictions lacked specificity.
"Tea is more than an aqueous infusion of caffeine and tannins: it has effects beyond what can be seen by gastroscope; one cannot describe its ancient popularity on the basis of its somewhat negligible vitamin and mineral content. Somehow the vital fraction remains undiscovered-or, perhaps there is no single missing factor, but merely the fortuitous combination of fractions which together produce something bigger and better than the simple addition of components."
Proceedings of the International Symposium on Tea Science
August 26-29, 1991. Shizuoka, Japan. In 1970, Nobel Prize double laureate (1954 Chemistry; 1962 Peace), Linus Pauling published a bestselling book entitled
Vitamin C and the Common Cold, announcing his belief that wise nutrition could prevent, ameliorate, or cure many diseases in addition to slowing the aging process. His theory proved far more popular with consumers--who soon began "megadosing" with the common vitamin--than with many of his scientific colleagues. Nonetheless, in 1991, scientist Bruce Ames and his colleagues substantiated vitamin C's protective effects in people. They attributed this to vitamin C's role as an antioxidant in fruits and vegetables, foods associated with lower rates of cancer. In modern day studies of the biochemistry of nutrition, antioxidant research has proliferated. This new nutritional concept emphasizing the protective values of antioxidants in the diet has elevated tea, particularly green, unfermented tea, into the millenium's newest health beverage. It has created new promotional material for old products such as Lipton Tea, and spawned entirely new industries and consumer loyalties. The twentieth century's Coca-Cola may well be paralleled in the twenty first century by Arizona Green Tea. Consumers frequently confuse true teas and herbal "teas." Technically, all tea consists of leaves taken from the tea plant. Leaves from any other kind of plant are herbals (or infusions when they are boiled in water). This Herbalife product lists tea as its primary ingredient so it is technically a tea, though it is called an herbal product. It makes no medical claims on its label and has a Nutrition Facts label indicating it is being marketed as a food (beverage).
Tempest in a Teapot: Tea & Politics & Health, Green Tea's Medical Resurgence
