Teas from leaves of Camellia sinensis, a small plant growing mainly in China and southeast Asia, are generally consumed in forms referred to as black, oolong, or green teas. Green tea is sold as fresh or dried leaves. The major polyphenol belonging to the family of catechins found in green tea is (-)-epigallocatechin gallate. Other catechins also present are catechin, epicatechin, gallocatechin (GC), GC gallate, epigallocatechin, and epicatechin gallate. The oxidation process used to prepare black tea converts many of the lower molecular weight catechin constituents in green tea leaves to more complex phenolics. The mild increase in thermogenesis associated with green tea intake is generally attributed to its caffeine content. Balb/c mice given green tea extract at a dose of 0.5% of their weight regularly over 10 weeks increased their endurance in exercise by up to 24%. Catechins and theaflavins seem to be responsible for many of the proposed benefits of tea.