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

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ClinicalTrials.gov Identifier: NCT01363869
Recruitment Status : Completed
First Posted : June 2, 2011
Last Update Posted : April 25, 2013
Sponsor:
Information provided by (Responsible Party):
Kanon Jatuworapruk, Chiang Mai University

Brief Summary:
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.

Condition or disease Intervention/treatment Phase
Hyperuricemia Gout Dietary Supplement: green tea extracts 2 gm/day Dietary Supplement: green tea extracts 4 gm/day Dietary Supplement: green tea extracts 6 gm/day Not Applicable

Detailed Description:

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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Study Type : Interventional  (Clinical Trial)
Actual Enrollment : 30 participants
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Treatment
Official Title: Effects of Green Tea on Level of Serum Uric Acid in Healthy Individuals
Study Start Date : June 2011
Actual Primary Completion Date : September 2012
Actual Study Completion Date : March 2013

Resource links provided by the National Library of Medicine

Genetics Home Reference related topics: Gout

Arm Intervention/treatment
Experimental: Green tea extracts 2 gm/day
Green tea extracts 2 gm/day for 14 days
Dietary Supplement: green tea extracts 2 gm/day

Green tea extracts capsule (1 gm per capsule), taken after meal, twice daily for 14 days.

Total dosage is 2 grams per day.


Experimental: Green tea extracts 4 gm/day
Green tea extracts 4 gm/day for 14 days
Dietary Supplement: green tea extracts 4 gm/day

Green tea extracts capsule (1 gm per capsule), taken after meal, twice daily for 14 days.

Total dosage is 4 grams per day.


Experimental: Green tea extracts 6 gm/day
Green tea extracts 6 gm/day for 14 days
Dietary Supplement: green tea extracts 6 gm/day

Green tea extracts capsule (1 gm per capsule), taken after meal, twice daily for 14 days.

Total dosage is 6 grams per day.





Primary Outcome Measures :
  1. serum uric acid [ Time Frame: 4 weeks (prior to, immediately after and 7 days after intervention) ]

Secondary Outcome Measures :
  1. urinary uric acid excretion [ Time Frame: 4 weeks (prior to, immediately after and 7 days after intervention) ]
  2. serum antioxidant activity [ Time Frame: 4 weeks (prior to, immediately after and 7 days after intervention) ]
  3. serum EGCG level [ Time Frame: 1 week (immediately after and 7 days after intervention) ]
    Measurements of serum level of epigallocatechin gallate (EGCG)

  4. Adverse events [ Time Frame: 4 week (prior to, immediately after and 7 days after intervention) ]
    Adverse events during 4-week study



Information from the National Library of Medicine

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Ages Eligible for Study:   18 Years and older   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   Yes
Criteria

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

Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT01363869


Locations
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Thailand
Department of Internal Medicine, Faculty of Medicine, Chiang Mai University
Chiang Mai, Thailand, 50200
Sponsors and Collaborators
Chiang Mai University
Investigators
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Principal Investigator: Kanon Jatuworapruk, M.D Department of Internal medicine, Faculty of Medicine, Chiang Mai University, Thailand

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Responsible Party: Kanon Jatuworapruk, Kanon Jatuworapruk M.D, Chiang Mai University
ClinicalTrials.gov Identifier: NCT01363869     History of Changes
Other Study ID Numbers: MED-11-02-07-13-X
First Posted: June 2, 2011    Key Record Dates
Last Update Posted: April 25, 2013
Last Verified: April 2013
Keywords provided by Kanon Jatuworapruk, Chiang Mai University:
hyperuricemia
gout
uric acid
xanthine oxidase inhibitor
green tea
catechins
antioxidant
Additional relevant MeSH terms:
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Hyperuricemia
Pathologic Processes
Uric Acid
Antioxidants
Molecular Mechanisms of Pharmacological Action
Protective Agents
Physiological Effects of Drugs