Comparative safety evaluation of Chinese Pu-erh green tea extract and Pu-erh black tea extract in Wistar rats.J Agric Food Chem. 2010 Jan 27; 58(2):1350-8.JA
Pu-erh teas are believed to be beneficial beverages for health since they possess several pharmacological properties such as antioxidation, hypocholesterolemia, and antiobesity properties, but their potential toxicities when administered at a high dose as concentrated extracts have not been completely investigated. In this study, the chemical components in Pu-erh green tea and Pu-erh black tea were analyzed and compared, and the safety of tea extracts was evaluated in Wistar rats. The polysaccharide, tea pigment, and flavonoid levels were substantially increased in the Pu-erh black tea, while the polyphenol and free amino acid levels were higher in unfermented green tea. Low toxicities of Pu-erh green tea extract (GTE) were observed at doses of 2500 and 5000 mg/kg/day with a 28-day subacute study. Serum biochemical data including alanine aminotransferase increased to 5000 mg/kg/day GTE males, and creatinine (Cr) increased in all 5000 mg/kg/day GTE groups and 2500 mg/kg/day GTE males. Slight bile duct hyperplasia in the liver was also observed. The target organs of GTE were considered to be the liver and kidney. Comparatively, no adverse effects were observed in Pu-erh black tea extract (BTE)-treated rats. In conclusion, a dose of 1250 mg/kg/day for GTE and 5000 mg/kg/day for BTE following oral administration could be considered safe under the conditions of this study.