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Effect of Quercetin Supplements on Healthy Males: a Four-Week Randomized Cross-Over Trial

This study has been completed.
Information provided by (Responsible Party):
Yuanlu Shi, University of Leeds Identifier:
First received: June 7, 2013
Last updated: March 20, 2015
Last verified: March 2015
The purpose of this study was to test the effect of chronic consumption of Quercetin 500 mg tablets on blood uric acid and other biomarkers in adult males.

Condition Intervention Phase
Kidney Calculi
Cardiovascular Disease
Dietary Supplement: Treatment
Dietary Supplement: Control
Early Phase 1

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double Blind (Participant, Investigator)
Primary Purpose: Basic Science
Official Title: A Double-Blind, Cross-Over, Placebo-Controlled Study Evaluating the Effect of Quercetin 500 mg Tablets on Blood Uric Acid in Healthy Males

Further study details as provided by Yuanlu Shi, University of Leeds:

Primary Outcome Measures:
  • Risk of getting hyperuricemia assessed by the measure of plasma uric acid. [ Time Frame: Fasting blood samples are taken on day 1, day 15 and day 29 of each arm ]
    The change of plasma uric acid level from day 1 on day 15 and day 29 of each arm.

Secondary Outcome Measures:
  • Kidney excretion of uric acid: urinary uric acid level [ Time Frame: 24 h urine samples are collected on day 14 and 28 of each arm and volume is recorded ]
    Difference in 24-h urinary uric acid level at 14 days and 28 days between arms

  • Blood pressure [ Time Frame: Blood pressure is measured on day 1 and 29 of each arm ]
    To monitor the compliance of subject.

  • Blood glucose [ Time Frame: Fasted blood samples are collected on day 1, 15, 29 of each arm ]
    The change of plasma glucose level from the baseline at day 15 and day 29 of each arm.

  • Metabolomic and metabonomic profiling of blood plasma [ Time Frame: Fasting blood samples are taken on day 1, day 15 and day 29 of each arm ]
    1H NMR (proton nuclear magnetic resonance )

Other Outcome Measures:
  • Urinary excretion of quercetin [ Time Frame: 24 h urine will be collected on day 14 and 28 of each arm and volume is recorded ]
    To monitor the compliance of subject.

  • Subject Body Weight [ Time Frame: weight is measured on day 1 and 29 of each arm ]
    To monitor the compliance of subject.

  • Subject Height [ Time Frame: Height is measured on day 1 and 29 of each arm ]
    To monitor the compliance of subject.

  • Life style maintenance [ Time Frame: Recall Questionnaires about the past 28 days are required on day 1 and 29 of each arm. ]
    To monitor the compliance of subject.

  • Primary health assessment [ Time Frame: Recall Questionnaires about history of certain disease, routine medication / supplements, allergies and exercise/diet practice at enrollment ]
    To set baseline for maintaining lifestyle and routine medicine for the study.

Enrollment: 22
Study Start Date: February 2013
Study Completion Date: November 2014
Primary Completion Date: April 2014 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Treatment
Daily intake of Quercetin supplement 500mg tablet for 28 days with meal (breakfast preferred.)
Dietary Supplement: Treatment
Address: Nature's Best, Century Place, Tunbridge Wells, Kent, TN2 3BE Phone:+44(0)1892 552030
Other Names:
  • Quercetin dihydrate 500 mg tablet
  • Brand: Nature's Best
  • Batch Number:114501
  • Serial Number: 5055148404901
Placebo Comparator: Placebo
Daily intake of Placebo (lactose) tablet for 28 days with meal (breakfast preferred)
Dietary Supplement: Control
Address: Fagron GmbH&Co. KG, 22885 Barsbuttel, Germany Phone: +49(0)4067067680
Other Names:
  • Placebo: lactose tablet
  • Brand: Fagron
  • Serial Number: PZN-0921071
  • Batch Number:1208D001A

Detailed Description:

The main goal of the research is to determine the long term effects of daily supplementation of quercetin, a compound naturally and normally present in food, on the chemical composition (uric acid ii and glucose) of blood and urine and on blood pressure, of healthy males.

Six of the volunteers will collect urine after consuming a standard meal made from fresh onion and after quercetin supplement intake, in the same way, with 3 days washout before each. The urine collected here will be analysed to check that the supplement is equivalent to the food. Stage 2 will only be conducted with supplement and placebo.

Healthy male volunteers with higher (than average) blood uric acid will be selected and will be asked to consume a standard supplement/placebo added to their own diet for 4 weeks per phase. Two arms are separated by 4 weeks resting period: quercetin supplement and placebo. Blood and urine samples will be taken every other week to detect any changes of uric acid and other biomarkers.

----- i) Quercetin is found in a variety of foods including apples, berries, brassica vegetables, capers, grapes, onions, shallots, tea, and tomatoes, as well as many seeds, nuts, flowers, barks, and leaves.

ii) Uric acid, a compound found in both in the human body and urine, is produced by the breakdown of purines, which are nitrogen-containing compounds in substances such as nucleic acids (DNA). They enter the circulation from digestion of certain foods, drinks (alcoholic beverages like beer and wine) or from normal breakdown and turnover of cells in the body. Most uric acid is removed by the kidneys and disposed of in the urine; the remainder is excreted in the stool.


Ages Eligible for Study:   19 Years to 65 Years   (Adult)
Sexes Eligible for Study:   Male
Accepts Healthy Volunteers:   Yes

Inclusion Criteria:

  • Written informed consent
  • Plasma Uric Acid > 300 micro Mole/L
  • Generally Healthy

Exclusion Criteria:

  • Body Mass Index (BMI) ≥ 30 kg/m² or <18.5 kg/m²
  • Unable or unwilling to comply with the protocol, or likely to leave the study before its completion.
  • Who would undertake important change in physical exercise or vigorous sport competitions during the study period.
  • regularly drink more than 3 units of alcohol every day
  • smokers
  • have history of treated hyperuricemia, gout and/ or kidney stone
  • have intestinal disorders
  Contacts and Locations
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Please refer to this study by its identifier: NCT01881919

United Kingdom
School of Food Science and Nutrition
Leeds, West Yorkshire, United Kingdom, LS2 9JT
Sponsors and Collaborators
University of Leeds
Study Chair: Gary Williamson, PhD University of Leeds
Principal Investigator: Yuanlu Shi, PhD Candidate University ofLeeds
  More Information

Additional Information:
Responsible Party: Yuanlu Shi, PhD Candidate, University of Leeds Identifier: NCT01881919     History of Changes
Other Study ID Numbers: MEEC12-019
Study First Received: June 7, 2013
Last Updated: March 20, 2015

Keywords provided by Yuanlu Shi, University of Leeds:
Functional Food

Additional relevant MeSH terms:
Cardiovascular Diseases
Kidney Calculi
Pathological Conditions, Anatomical
Pathologic Processes
Kidney Diseases
Urologic Diseases
Urinary Calculi
Molecular Mechanisms of Pharmacological Action
Protective Agents
Physiological Effects of Drugs processed this record on May 25, 2017