Tier 2 — strong

Quercetin reduces illness but not immune perturbations after intensive exercise

David C Nieman, Dru A Henson, Sarah J Gross, David P Jenkins, J Mark Davis, E Angela Murphy, Martin D Carmichael, Charles L Dumke, Alan C Utter, Steven R McAnulty, Lisa S McAnulty, Eugene P Mayer
Medicine and science in sports and exercise 2007 39(9):1561

Bibliography

PubMed
PMID 17805089
DOI
10.1249/mss.0b013e318076b566
Funding
Funding was not specified in the indexed record or the disclosure metadata available for this entry.
Competing interests
A competing-interest declaration was not available in the indexed record or the disclosure metadata used for this entry.

Study snapshot

DesignRandomized double-blind placebo-controlled exercise and illness trial
ModelHuman intervention research
Sample40 trained male cyclists
InterventionQuercetin 1,000 mg/day or placebo
Duration3 weeks before intensified exercise and 2 weeks afterward
EndpointsSource-specific outcomes described in the key findings

What the study showed, in plain terms

Published in 2007, this source examined immunity and respiratory health. Design: Randomized double-blind placebo-controlled exercise and illness trial. Sample/model: 40 trained male cyclists. The exposure or intervention was Quercetin 1,000 mg/day or placebo. Follow-up or treatment period: 3 weeks before intensified exercise and 2 weeks afterward.

Reported upper-respiratory illness occurred in 1 of 20 quercetin recipients versus 9 of 20 placebo recipients; exercise-related immune-function changes did not differ.

Small illness-event count and a specialized exercise setting limit generalization. The immune assays did not show the proposed broad improvement.

Continue with Quercetin Data Center

For topic-level interpretation, read Quercetin for Immune Health, Colds and COVID-19. This is a related guide; the citation panel separately identifies articles that directly cite this paper.

Key findings

  • Reported upper-respiratory illness occurred in 1 of 20 quercetin recipients versus 9 of 20 placebo recipients; exercise-related immune-function changes did not differ.
  • The recorded outcome domains were Source-specific outcomes described in the key findings.
  • The result applies to the tested exposure: Quercetin 1,000 mg/day or placebo; 3 weeks before intensified exercise and 2 weeks afterward.

What this study can and cannot tell us

  • Small illness-event count and a specialized exercise setting limit generalization. The immune assays did not show the proposed broad improvement.
  • An individual controlled trial must be interpreted alongside its comparator, sample size, endpoint selection and independent replication. It does not validate a different commercial formulation or a general longevity claim.
  • Source basis: Source check: PubMed abstract and indexed metadata; full methods were not independently confirmed for this entry. Missing method details, funding information or participant denominators are not inferred.

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Citation network

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Dr. Khaled Mahmoud, MBBChCritical Care Medicine, Longevity Science & Editorial Direction Dr. Amr Yasser, PhDCardiometabolic, Musculoskeletal, Gut & Bioavailability Dr. Abdulla Mostafa, PhDCellular Senescence, Neurological, Mitochondrial & Brain-Ageing Biology