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Components of Tea: Catechins and Caffeine
Flavonoids are dietary compounds found in tea and other foods such as wine, cocoa, fruits and vegetables. Flavonoids determine the color and taste of food and may be involved in healthy body functions. The average U.S. adult consumes 189.7 milligrams of flavonoids each day, most of which (157 mg to be exact) come from tea. While there is currently no recommendation for flavonoid consumption, experts are in the initial stages of discussion regarding recommendations for these dietary components. Tea contains approximately 100-300 milligrams of flavonoids per serving, depending on the type of tea. The main type of flavonoids found in tea are catechins. Because the green tea variety is less processed, it contains more catechins than black tea does. Therefore green tea and green tea extracts have received the most research regarding possible health benefits and will be the focus of this particular article. Research has primarily investigated the health benefits of catechins such as epigallocatechin gallate (EGCG), epigallocatechin (EGC), epicatechin gallate (ECG), and epicatechin (EC).
Green tea also contains 2% to 4% caffeine or about 10-80 milligrams per cup. (For reference, a cup of regular coffee contains 95 mg of caffeine, while 1 oz. of dark chocolate contains 23 mg.) Caffeine has also been the topic of many research studies regarding the health benefits of green tea.
Health Benefits of Green Tea: What the Research Really Shows
The research to date indicates that green tea is likely effective for: