Beneficial Effects of Green Tea—A Review

Abstract

Tea is the most consumed drink in the world after water. Green tea is a 'non-fermented' tea, and contains more catechins, than black tea or oolong tea. Catechins are in vitro and in vivo strong antioxidants. In addition, its content of certain minerals and vitamins increases the antioxidant potential of this type of tea. Since ancient times, green tea has been considered by the traditional Chinese medicine as a healthful beverage. Recent human studies suggest that green tea may contribute to a reduction in the risk of cardiovascular disease and some forms of cancer, as well as to the promotion of oral health and other physiological functions such as anti-hypertensive effect, body weight control, antibacterial and antivirasic activity, solar ultraviolet protection, bone mineral density increase, anti-fibrotic properties, and neuroprotective power. Increasing interest in its health benefits has led to the inclusion of green tea in the group of beverages with functional properties. However, although all the evidence from research on green tea is very promising, future studies are necessary to fully understand its contributions to human health, and advise its regular consumption in Western diets, in which green tea consumption is nowadays limited and sporadic.

Possible protective effect of green tea intake on risk of adult leukaemia

“…If tea leaves are immediately heated, then the enzymes that oxidise catechins are inactivated and the result is green tea; if crushed and allowed to undergo enzyme-mediated oxidation, the process results in black tea with its characteristic colour and taste. Oolong tea results from partially oxidised tea leaves (Graham, 1992).There is some evidence of a protective effect of green tea consumption on certain cancers (Zhang et al, 2002;2004;2007;Cabrera et al, 2006), but no epidemiological data are available on the effect of green tea on adult leukaemia. We therefore conducted a case -control study of the question in southeast China.…”

Inhibitory activity of a green and black tea blend on Streptococcus mutans

“…Aside from water, tea is the most commonly consumed beverage in the human diet [1]. Tea is obtained from processing the tender leaves and buds of the Camellia sinensis plant.…”

“…Depending on the manufacturing process different types of tea are obtained. Green tea is obtained by withering the C. sinensis leaves to remove moisture followed by steam treatment to inactivate enzymes in the tea leaves [1]. Green tea is characterized by the presence of non-oxidized phenolic compounds named catechins, which are the mainly responsible for the antioxidant capacity of green tea [2,3].…”

“…In black tea, C. sinensis leaves are first withered to remove moisture and then rolled and allowed to ferment. This process results in the oxidation of the leaves by enzymes present in the tea leaves and conversion of the catechins to higher molecular weight polyphenolic compounds such as theaflavins and thearubigins that give black tea the distinctive colour and flavor [1]. Non-catechin components, such as tannins and thearubigins, are the main components responsible for the antioxidant activity of black tea [2].…”

“…Many published studies have established correlations between the intake of green and black tea and several benefits mainly linked to the reduction of oxidative stress and inflammation reviewed in [reviewed in 1,5–8]. Tea benefits can also be linked to skin health, weight management and muscle recovery [9–12].…”