Tea is one of the oldest drinks (used
for almost 50 centuries in Asia) and – after water – the most common
beverage people enjoy the world over (Mandel et al. 2008). Native to
China, it comes from the evergreen plantCamellia sinensis. A cup
of tea contains numerous compounds in varying quantities: vitamins,
polyphenols, caffeine, fluoride, sugars, amino acids, proteins,
minerals, chlorophyll and others (Zhao et al. 2013). Which tea is
produced (white, green, oolong or black) depends on the subsequent
processing of harvested Camellia leaves. Teas can be classified as non-fermented (green and white teas), semi-fermented (oolong tea), and fermented (black tea).
The health promoting effects of green tea are
attributed to the rich antioxidant polyphenol content of its leaves
(flavonols & catechins), making up c. 30% dry weight of a tea leaf,
and exhibiting biochemical and pharmacological activities (Siddiqui et
al. 2006). Recently, many of these beneficial effects were traced back
to the most abundant catechin, EGCG (Wolfram 2007).