Medicinal Benefits of Green Tea: Part I. Review of Noncancer Health Benefits

Abstract

Tea, in the form of green or black tea, is one of the most widely consumed beverages in the world. Extracts of tea leaves also are sold as dietary supplements. However, with the increasing interest in the health properties of tea and a significant rise in scientific investigation, this review covers recent findings on the medicinal properties and noncancer health benefits of both green and black tea. In Part II, a review of anticancer properties of green tea extracts is presented. Green tea contains a unique set of catechins that possess biological activity in antioxidant, anti-angiogenesis, and antiproliferative assays potentially relevant to the prevention and treatment of various forms of cancer. Although there has been much focus on the biological properties of the major tea catechin epigallocatechin gallate (EGCg) and its antitumor properties, tea offers other health benefits; some due to the presence of other important constituents. Characteristics unrelated to the antioxidant properties of green and black teas may be responsible for tea's anticancer activity and improvement in cardiac health and atherosclerosis. Theanine in green tea may play a role in reducing stress. Oxidized catechins (theaflavins in black tea) may reduce cholesterol levels in blood. Synergistic properties of green tea extracts with other sources of polyphenolic constituents are increasingly recognized as being potentially important to the medicinal benefits of black and green teas. Furthermore, due to presumed antioxidant and antiaging properties, tea is now finding its way into topical preparations. Each of these aspects is surveyed.

The influence of stereochemistry on the antioxidant properties of catechin epimers

“…In food, they are present as mono-, oligo-, or polymers at the level ranging from 10 to 250 mg/kg in fruits, 610 mg/kg in dark chocolate to 850-2,200 mg/l in green tea infusion [1,4,5]. A relatively high level of catechins in the human diet is often correlated with reduced risk of common chronic diseases such as cancer or cardiovascular disease [6][7][8][9]. Beneficial health effects of catechins are mainly ascribed to their antioxidant activity [8,9].…”

“…A relatively high level of catechins in the human diet is often correlated with reduced risk of common chronic diseases such as cancer or cardiovascular disease [6][7][8][9]. Beneficial health effects of catechins are mainly ascribed to their antioxidant activity [8,9].…”

Green tea catechins for treatment of external genital warts

“…Later, in the Kissa Yojoki (Book of Tea, ca 1191), tea was listed as a remedy to control bleeding, help wounds heal, regulate body temperature, control blood sugar, and promote digestion. 2,3 Green tea, which constitutes 20% of the tea manufactured worldwide, is probably the most consumed beverage besides water in Asian society ( Figure 1). The main substances found in green tea are caffeine (2-4%), amino acids (4%), lignin (6.5%), organic acids (1.5%), protein (15%), chlorophyll (0.5%), and the polyphenols (25-35%).…”

Comparison of antioxidant capacities of different types of tea using the spectroscopy methods and semi-empirical mathematical model

“…Tea is one of the most widely consumed beverages in the world [7]. It is valued both for the taste and for the health benefits associated with its antioxidant content [1,[7][8][9][10]. All varieties of tea are produced from young, tender leaves of Camellia sinensis (L.) (family Theaceae).…”