Health experts reckon three cups of tea per day is the optimal anti-aging number. A study conducted by a team at Sichuan University in Chengdu, China surveyed 5,998 British people aged 37 to 73 in addition to 7,931 people in China between the ages of 30 and 79 regarding their tea-drinking habits. The researchers asked participants whether they drank green, yellow, black, or oolong tea.