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Green tea has been extensively investigated for several potential health benefits. Previous studies have suggested that green tea may lower serum uric acid level in human. The purpose of this study is to investigate uric-lowering properties of green tea 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.
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| Label | Type | Description | Intervention Names |
|---|---|---|---|
| Green tea extracts 2 gm/day | Experimental | Green tea extracts 2 gm/day for 14 days |
|
| Green tea extracts 4 gm/day | Experimental | Green tea extracts 4 gm/day for 14 days |
|
| Green tea extracts 6 gm/day | Experimental | Green tea extracts 6 gm/day for 14 days |
|
| Name | Type | Description | Arm Group Labels | Other Names |
|---|---|---|---|---|
| green tea extracts 2 gm/day | Dietary Supplement | Green tea extracts capsule (1 gm per capsule), taken after meal, twice daily for 14 days. Total dosage is 2 grams per day. |
|
| Measure | Description | Time Frame |
|---|---|---|
| serum uric acid | 4 weeks (prior to, immediately after and 7 days after intervention) |
| Measure | Description | Time Frame |
|---|---|---|
| urinary uric acid excretion | 4 weeks (prior to, immediately after and 7 days after intervention) | |
| serum antioxidant activity | 4 weeks (prior to, immediately after and 7 days after intervention) | |
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Inclusion Criteria:
Exclusion Criteria:
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| Name | Affiliation | Role |
|---|---|---|
| Kanon Jatuworapruk, M.D | Department of Internal medicine, Faculty of Medicine, Chiang Mai University, Thailand | Principal Investigator |
| Facility | Status | City | State | ZIP | Country | Contacts |
|---|---|---|---|---|---|---|
| Department of Internal Medicine, Faculty of Medicine, Chiang Mai University | Chiang Mai | Chiang Mai | 50200 | Thailand |
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| ID | Term |
|---|---|
| D033461 | Hyperuricemia |
| D006073 | Gout |
| ID | Term |
|---|---|
| D010335 | Pathologic Processes |
| D013568 | Pathological Conditions, Signs and Symptoms |
| D001168 | Arthritis |
| D007592 | Joint Diseases |
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| green tea extracts 4 gm/day | Dietary Supplement | Green tea extracts capsule (1 gm per capsule), taken after meal, twice daily for 14 days. Total dosage is 4 grams per day. |
|
| green tea extracts 6 gm/day | Dietary Supplement | Green tea extracts capsule (1 gm per capsule), taken after meal, twice daily for 14 days. Total dosage is 6 grams per day. |
|
| serum EGCG level |
Measurements of serum level of epigallocatechin gallate (EGCG) |
| 1 week (immediately after and 7 days after intervention) |
| Adverse events | Adverse events during 4-week study | 4 week (prior to, immediately after and 7 days after intervention) |
| D009140 | Musculoskeletal Diseases |
| D000070657 | Crystal Arthropathies |
| D012216 | Rheumatic Diseases |
| D011686 | Purine-Pyrimidine Metabolism, Inborn Errors |
| D008661 | Metabolism, Inborn Errors |
| D030342 | Genetic Diseases, Inborn |
| D009358 | Congenital, Hereditary, and Neonatal Diseases and Abnormalities |
| D008659 | Metabolic Diseases |
| D009750 | Nutritional and Metabolic Diseases |