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

Study Overview
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Brief Summary
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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.

Detailed Description
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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.

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

Conditions
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Hyperuricemia, Gout

Intervention / Treatment
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* Dietary Supplement: green tea extracts 2 gm/day
* Dietary Supplement: green tea extracts 4 gm/day
* Dietary Supplement: green tea extracts 6 gm/day


Participation Criteria
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Eligibility Criteria
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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

Ages Eligible for Study
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Minimum Age: 18 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Green tea extracts 2 gm/day<br>Green tea extracts 2 gm/day for 14 days | Dietary Supplement: green tea extracts 2 gm/day<br>* Green tea extracts capsule (1 gm per capsule), taken after meal, twice daily for 14 days. Total dosage is 2 grams per day.<br>|
| Experimental: Green tea extracts 4 gm/day<br>Green tea extracts 4 gm/day for 14 days | Dietary Supplement: green tea extracts 4 gm/day<br>* Green tea extracts capsule (1 gm per capsule), taken after meal, twice daily for 14 days. Total dosage is 4 grams per day.<br>|
| Experimental: Green tea extracts 6 gm/day<br>Green tea extracts 6 gm/day for 14 days | Dietary Supplement: green tea extracts 6 gm/day<br>* Green tea extracts capsule (1 gm per capsule), taken after meal, twice daily for 14 days. Total dosage is 6 grams per day.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| serum uric acid |  | 4 weeks (prior to, immediately after and 7 days after intervention) | 

Secondary Outcome Measures

| Outcome Measure | 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) | 
| 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) | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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green tea, hyperuricemia, gout, uric acid, xanthine oxidase inhibitor, catechins, antioxidant