Tea plants are among the plants with the highest total flavonoid content. 93% of total tea phenolic compounds are flavonoids. Green tea contains more simple flavonoids (called catechins), while black tea contains more complex varieties (called theflavins and thearubigins). The longer tea is left to brew, the higher the concentration of flavonoids.
For many years, it has been known that tea plant polyphenols are antioxidant. In fact, many common flavonoids are several times more potent than Vitamin C or E 12, 13. Growing interest in the antioxidant activity of phenolic compounds has led to increased research into potential health benefits.
(Source: Tea Board Kolkata)