Tier 2 — strong

Immune Preconditioning with Oral Quercetin Supplement and COVID-19 mRNA Vaccine Responses: A Randomized, Double-Blind, Placebo-Controlled Trial

Shokichi Takahama, Takuto Nogimori, Aiko Tanaka, Ayae Nishiyama, Shingo Iwami, Keiichi Abe, Jun Nishihira, Takuya Yamamoto
The Journal of nutrition 2026 156(4):101431

Bibliography

PubMed
PMID 41759822
DOI
10.1016/j.tjnut.2026.101431
Funding
Funding was not specified in the indexed record or the disclosure metadata available for this entry.
Competing interests
Reported disclosure: TY reports financial support was provided by Japan Society for the Promotion of Science. KA is an employee of the Research Foundation for Microbial Diseases of Osaka University. All other authors report no conflicts of interest.

Study snapshot

DesignRandomized double-blind placebo-controlled trial
ModelHuman intervention research
Sample50 analyzed participants: 24 quercetin glycoside and 26 placebo
InterventionTwo capsules daily, each containing 280 mg ±5% quercetin-glycoside complex
Duration4 weeks before vaccination; 3-month immune follow-up
EndpointsSource-specific outcomes described in the key findings

What the study showed, in plain terms

Published in 2026, this source examined immunity and respiratory health. Design: Randomized double-blind placebo-controlled trial. Sample/model: 50 analyzed participants: 24 quercetin glycoside and 26 placebo. The exposure or intervention was Two capsules daily, each containing 280 mg ±5% quercetin-glycoside complex. Follow-up or treatment period: 4 weeks before vaccination; 3-month immune follow-up.

The supplement did not significantly change vaccine antibody responses, antigen-specific T-cell responses or vaccine reactions.

Formulation mass is not an equivalent dose of pure quercetin. Numerical temperature differences were not significant.

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

  • The supplement did not significantly change vaccine antibody responses, antigen-specific T-cell responses or vaccine reactions.
  • The recorded outcome domains were Source-specific outcomes described in the key findings.
  • The result applies to the tested exposure: Two capsules daily, each containing 280 mg ±5% quercetin-glycoside complex; 4 weeks before vaccination; 3-month immune follow-up.

What this study can and cannot tell us

  • Formulation mass is not an equivalent dose of pure quercetin. Numerical temperature differences were not significant.
  • 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.

Related papers in the corpus

Tier 2
The therapeutic efficacy of quercetin in combination with antiviral drugs in hospitalized COVID-19 patients: A randomized controlled trial
Mojtaba Shohan et al. · European journal of pharmacology · 2022
Tier 2
Oral Co-Supplementation of Curcumin, Quercetin, and Vitamin D3 as an Adjuvant Therapy for Mild to Moderate Symptoms of COVID-19-Results From a Pilot Open-Label, Randomized Controlled Trial
Amjad Khan et al. · Frontiers in pharmacology · 2022
Tier 2
Quercetin as a possible complementary agent for early-stage COVID-19: Concluding results of a randomized clinical trial
Francesco Di Pierro et al. · Frontiers in pharmacology · 2022

Citation network

Articles citing this research paper

1 article

Biohack Blueprint analyses that reference this study in their evidence base.

Editorial review

Reviewed by the Biohack Blueprint research team

Last verified

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