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Randomised clinical trial to determine the safety of quercetin supplementation in patients with chronic obstructive pulmonary disease
  1. Meilan K Han1,
  2. Tyler A Barreto2,
  3. Fernando J Martinez3,
  4. Adam T Comstock4 and
  5. Umadevi S Sajjan2,5
  1. 1Internal Medicine, University of Michigan, Ann Arbor, Michigan, USA
  2. 2Thoracic Medicine and Surgery, Temple University Medical School, Philadelphia, Pennsylvania, USA
  3. 3Medicine, Weill Cornell Medical College, New York, New York, USA
  4. 4Pediatrics, University of Michigan, Ann Arbor, Michigan, USA
  5. 5Physiology, Lewis Katz Medical School, Temple University, Philadelphia, PA, USA
  1. Correspondence to Dr Umadevi S Sajjan; uma.sajjan{at}


Introduction Quercetin is a plant flavonoid and has potent antioxidant and anti-inflammatory properties. In a preclinical model of chronic obstructive pulmonary disease (COPD), quercetin reduced markers of both oxidative stress and lung inflammation and also reduced rhinovirus-induced progression of lung disease. Although quercetin appears to be an attractive natural alternative to manage COPD, the safety of quercetin supplementation in this population is unknown.

Methods We recruited COPD patients with mild-to-severe lung disease with FVE1 ranging between >35% and <80% and supplemented with either placebo or quercetin at 500, 1000 or 2000 mg/day in a dose-escalation manner. The duration of quercetin supplementation was 1 week.

Results Patients had no study drug-related severe adverse events based on blood tests, which included both complete blood counts and evaluation of comprehensive metabolic panel. One of the patients reported mild adverse events included gastro-oesophageal reflux disease, which was observed in both placebo and quercetin groups.

Conclusions Quercetin was safely tolerated up to 2000 mg/day as assessed by lung function, blood profile and COPD assessment test questionnaire.

Trial registration number NCT01708278

  • complementary medicine
  • oxidative stress

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  • Contributors MH, clinical investigator, designed and conducted the study and finalised the manuscript. TAB compiled the data and prepared the tables for the manuscript. FJM designed the study. ATC developed the database and entered the data. US conceived and designed the study and prepared the manuscript.

  • Competing interests None declared.

  • Patient consent for publication Not required.

  • Ethics approval The study was conducted according to modified Declaration of Helsinki under the approval of the institutional review board of University of Michigan, Ann Arbour (IRB#HUM00061735).

  • Provenance and peer review Not commissioned; externally peer reviewed.

  • Data availability statement Data are available upon reasonable request.