Green tea is made from unoxidized leaves that are heated immediately after plucking. Bypassing the oxidation process allows the leaves to retain their green color and the antioxidants and polyphenols that have powerful, beneficial effects on the body. Green tea produces a more astringent and subtler taste than oolong and black teas. It has a lower caffeine content (around 25-40 mg per 8 oz) and therefore is a steady, mild stimulant.