Effects of Green Tea on Level of Serum Uric Acid in Healthy Individuals

Elevated serum uric acid is related to the risk of development of gout, the most common inflammatory arthritis in men. Allopurinol, a xanthine oxidase inhibitor, is one of the uric-lowering agents commonly used in patients suffering from recurrent and chronic gout. Nevertheless, its use is limited by adverse effects and serious allergic reaction in some patients.

Green tea is one of the most frequently consumed beverages, particularly in Japan. Green tea contains high level of catechins, in which Epigallocatechin gallate (EGCG) is the most abundant compound among other types of catechins. Antioxidant effect contributes to various potential health benefits of green tea. Several in-vitro studies have found that green tea inhibits xanthine oxidase activity and subsequently decreases reactive oxygen species (ROS) and uric acid production. We therefore would like to investigate the hypouricemic effects of green tea.

The study consists of three periods with a total duration of four weeks. The first week is the control period. The following two weeks is the interventional period and the last week is the follow up period. Thirty healthy participants will be randomly assigned into three experimental groups, receiving 2 gm/day, 4 gm/day and 6 gm/day (in capsule, two times after meal) of green tea extract during interventional period. Blood and urine samples will be taken at the beginning and at the end of each study period.

Inclusion criteria

• Age 18 years or older
• Healthy individuals
• Normal renal and liver function from blood tests

Exclusion criteria

• Presence of co-morbidity or currently ill
• Currently using any medication or nutritional supplement product that may affect serum uric acid level
• Serum creatinine higher than 1.5 mg/dl
• Abnormal serum Aspartate aminotransferase (AST) and/or Alanine transaminase (ALT)
• Greater than 15% change in serum uric acid during control period