a's dry weight, translating to between 30 and 90 milligrams per 250-මිලිlitre (8 1⁄2 US fl oz) cup depending on the type, brand,[49] and brewing method.[50] A study found that the caffeine content of one gram of black tea ranged from 22 to 28 mg, while the caffeine content of one gram of green tea ranged from 11 to 20 mg, reflecting a significant difference.[51] Tea also contains small amounts of theobromine and theophylline, which are stimulants, and xanthines similar to caffeine.[52]Fresh tea leaves in various stages of growthThe astringency in tea can be attributed to the presence of polyphenols. These are the most abundant compounds in tea leaves, making up 30–40% of their composition.[53] Polyphenols include flavonoids, epigallocatechin gallate (EGCG), and other catechins.[54][55] Although there has been preliminary clinical research on whether green or black teas may protect against various human diseases, there is no evidence that tea polyphenols have any effect on health or 