ABSTRACT
Polyphenols are found in a variety of beverages that have been manufactured from plant materials, including fruit juices, red wine, and black and green tea. Flavonoids are the largest group of polyphenols and as discussed elsewhere in this book are divided into anthocyanins, avones, isoavones, avan-3-ols, avans, and avonols (Buttereld et al. 2002). Flavan-3-ols, sometimes referred to as catechins, account for 30-40% of the dry weight of the leaves of green tea (Yang and Wang 1993; Wang et al. 1994). Green tea belongs to the Theacease family one of which is Camellia sinensis (Graham 1992), the most widely consumed beverage (aside from water) in Japan, China, and other Asian nations and is presently becoming ever more popular in Western countries. The rst historical reports of the medicinal properties of green tea appeared in the 16th century, where extracts were used as therapeutic agents to treat fever, headache, and stomach pains (Sutherland et al. 2006). The intake of green tea is generally regarded as being safe (authorized as such by the U.S. Food and Drug Administration) (Wu and Wei 2002) and has attracted attention for its health benets in humans, particularly with respect to its potential for preventing and treating cancer, inammatory diseases, cardiovascular diseases, neurodegenerative diseases, impaired metabolism, diabetes, stroke, and aging (Figure 15.1). For more information on these, please refer to reviews by Hollman et al. (1999), Weisburger and Chung (2002), Mandel et al. (2004b, 2005), Weinreb et al. (2004), Lau et al. (2005), Cabrera et al. (2006), Rossi et al. (2008), and Spencer (2008).
