Caffeine content of common beverages.

Tea, coffee, carbonated and chocolate beverages were analyzed for caffeine, and results compared in terms of usual serving sizes. Significant differences in caffeine levels were found to result from the preparation method of coffee or brewing time of tea. It is possible for a cup of tea, instant coffee, or can of cola beverage to have similar caffeine content (55 to 65 mg.); however, the mean values per cup of black tea (28 to 46 mg.) are considerably lower than for brewed coffee (107 to 151 mg.). Caffeine is readily absorbed and can have pharmacologic effects on adults or on children who consume quantities of cola beverages or chocolate. Both preparation method and quantity of beverage consumed should be considered in taking dietary histories or estimating caffeine intake.