Two new studies in Hong Kong and Japan universities report more benefits of tea drinking. Green tea contains 30%-40% of polyphenols which act as potent antioxidants, while black tea 3%-10%. From the Hong Kong study - people who drank an average of 3 cups of (mainly green) tea per day potentially added 5 years to their lifespan. In the Japanese study, people who drank 7 or more cups of green tea a day could reduce the risk of heart disease mortality by an 75% and reduce the risk of colorectal cancer mortality of 31%.