![]() ![]() In one of these studies in Taiwan ( Wu et al., 2003), a lower percentage of total body fat, smaller waist circumference and decreased waist-to-hip ratio were observed in subjects with average habitual tea consumption of 434 mL/day for more than 10 years, compared to non-habitual tea drinkers. The majority of evidence associated with green tea consumption and health benefits come from epidemiological studies. This chapter highlights the recent research on the efficacy and mechanisms of action of GTCs on body weight, fat metabolism and oxidative stress parameters, with particular interest in their application in healthy, physically active and trained individuals. However, it is not known so far whether these effects on molecular endpoints in signal transduction pathways are downstream events of the modulation of pro-oxidant/antioxidant balance in cells or if they result from direct action of the catechins on molecular targets, independent of antioxidant properties ( Zaveri, 2006). In addition to antioxidant effects, GTCs have been purported to influence several molecular targets in signal transduction pathways associated with cell death and survival ( Murase et al., 2002). The health benefits of green tea are mainly attributed to its anti-oxidant properties, including the ability of catechins to scavenge reactive oxygen species or chelate with metal ions ( Kashima, 1999). In addition to the antioxidant properties of the catechins, their anti-diabetic, anti-bacterial, anti-inflammatory and anti-obesity activities also have been reported ( Zaveri, 2006). In recent years, many health benefits of consuming green tea have been reported, including the prevention of diseases associated with free radicals and reactive oxygen species, such as cancer, or cardiovascular and neurodegenerative diseases. Therefore, standardised green tea extract (GTE) has been developed for research to provide uniform levels of green tea catechins (GTCs). However, the concentration of bioactive compounds of green tea can vary widely according to preparation methods, that is, brewing time or water temperature ( Rains et al., 2011). A typical brewed green tea beverage (250 mL) contains 50–100 mg of catechins and 30–40 mg of caffeine. In addition, caffeine, theanine, theaflavins and phenolic acids such as gallic acid are present in smaller quantities (Cooper et al., 2005). The predominant constituents of green tea are polyphenols belonging to the family of catechins, mainly (‒)-epigalocatechin gallate (EGCG), with lesser amounts of catechin (C), epicatechin (EC), epigalocatechin (EGC) and epicatechin gallate (ECG). Green tea is brewed from the unfermented dried leaves of the plant Camellia sinensis. ![]()
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