Tier 2 — strong

Quercetin significantly inhibits the metabolism of caffeine, a substrate of cytochrome P450 1A2 unrelated to CYP1A2*1C  (-2964G>A) and *1F (734C>A) gene polymorphisms

Jian Xiao, Wei-Hua Huang, Jing-Bo Peng, Zhi-Rong Tan, Dong-Sheng Ou-Yang, Dong-Li Hu, Wei Zhang, Yao Chen
BioMed research international 2014 2014:405071

Bibliography

PubMed
PMID 25025048
PubMed Central
PMC4082882
DOI
10.1155/2014/405071
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

DesignTwo-phase human pharmacokinetic interaction study
ModelHuman intervention research
Sample12 healthy volunteers in two CYP1A2 genotype groups
InterventionQuercetin 500 mg/day for 13 days; caffeine 100 mg with quercetin on day 14
DurationTwo phases separated by 2 weeks
EndpointsExposure and pharmacokinetics

What the study showed, in plain terms

Published in 2014, this source examined safety, interactions and special populations. Design: Two-phase human pharmacokinetic interaction study. Sample/model: 12 healthy volunteers in two CYP1A2 genotype groups. The exposure or intervention was Quercetin 500 mg/day for 13 days; caffeine 100 mg with quercetin on day 14. Follow-up or treatment period: Two phases separated by 2 weeks.

Quercetin inhibited caffeine metabolism under the tested schedule; the two selected genotype groups did not differ significantly.

Small genotype-specific sample. The study does not quantify interaction risk for every CYP1A2 substrate or consumer caffeine pattern.

Continue with Quercetin Data Center

For topic-level interpretation, read Quercetin Interactions: Medicines, Evidence and Precautions. This is a related guide; the citation panel separately identifies articles that directly cite this paper.

Key findings

  • Quercetin inhibited caffeine metabolism under the tested schedule; the two selected genotype groups did not differ significantly.
  • The recorded outcome domains were Exposure and pharmacokinetics.
  • The result applies to the tested exposure: Quercetin 500 mg/day for 13 days; caffeine 100 mg with quercetin on day 14; Two phases separated by 2 weeks.

What this study can and cannot tell us

  • Small genotype-specific sample. The study does not quantify interaction risk for every CYP1A2 substrate or consumer caffeine pattern.
  • A change in blood exposure or a metabolic marker is not a demonstrated improvement in symptoms, disease events or lifespan. The tested formulation and co-administered medicines matter.
  • 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
Phase 1 study of quercetin, a natural antioxidant for children and young adults with Fanconi anemia
Parinda A Mehta et al. · Blood advances · 2025
Tier 2
Randomised clinical trial to determine the safety of quercetin supplementation in patients with chronic obstructive pulmonary disease
Meilan K Han et al. · BMJ open respiratory research · 2020
Tier 2
Interaction study between antiplatelet agents, anticoagulants, diabetic therapy and a novel delivery form of quercetin
Antonella Riva et al. · Minerva cardioangiologica · 2019

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