Flavonoids are natural antioxidants found in various foods. Citrus fruits, cocoa, dark chocolate, blueberries, strawberries, and spinach are all dietary sources rich in flavonoids. One major source is black tea. An American Journal of Epidemiology study examined the connections between flavonoid intake, black tea consumption, and prostate cancer risk.
Researchers used the Netherlands Cohort study which includes over 58,000 men who provided thorough baseline information on several cancer risk factors. Intake of total flavonoids and consumption of black tea were associated with a decreased risk of advanced prostate cancer.