Green tea has been used in traditional Indian and Chinese medicine and considered one of the world's healthiest drinks. Green tea is high in protective polyphenols. The major polyphenols in green tea are flavonoids, the most active of which are catechins and epigallocatechin gallate which act as powerful antioxidants. Green tea does contain caffeine which can increase energy levels, concentration and mood. Sencha is the most popular of Green Teas. Temperature and steeping time all have significant effects on the antioxidant levels of brewed green tea. Warm and ambient temperatures are the best to retain antioxidants.