Determination of methylxanthine contents and risk characterisation for various types of tea in Korea

Tea leaves contain methylxanthines, such as caffeine, which have various physiological and pharmacological effects in vivo. Caffeine, theobromine and theophylline were analysed in various teas to determine the exposure amount and health risk of methylxanthine intake from tea. All the determined validation parameters of the HPLC analysis method, which included specificity, linearity of the calibration curve, detection limit, reproducibility and accuracy, showed satisfactory results. When 83 leached extracts of 11 different teas were analysed by the HPLC method, the average contents of caffeine, theobromine and theophylline were 5561.5, 407.3 and 24.8 mg/kg, respectively. Pu-erh tea contained the highest average levels of caffeine, while hibiscus tea presented the highest average levels of theobromine and theophylline. Based on the seventh Korea National Health and Nutrition Examination Survey data on food intake, the daily intake of caffeine, theobromine and theophylline was calculated as 30.819, 1.408 and 0.011 μg/kg body weight/day, respectively, showing low levels of methylxanthine intake compared to the recommended daily intakes.