Tier 2 — strong

Quercetin from shallots (Allium cepa L. var. aggregatum) is more bioavailable than its glucosides

Wieslaw Wiczkowski, Jerzy Romaszko, Adam Bucinski, Dorota Szawara-Nowak, Joanna Honke, Henryk Zielinski, Mariusz K Piskula
The Journal of nutrition 2008 138(5):885

Bibliography

PubMed
PMID 18424596
DOI
10.1093/jn/138.5.885
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 crossover food-matrix absorption study
ModelHuman intervention research
Sample9 volunteers
InterventionShallot flesh or dried shallot skin, each providing 1.4 mg quercetin/kg
DurationSingle-dose comparisons
EndpointsExposure and pharmacokinetics

What the study showed, in plain terms

Published in 2008, this source examined forms, absorption and food sources. Design: Randomized crossover food-matrix absorption study. Sample/model: 9 volunteers. The exposure or intervention was Shallot flesh or dried shallot skin, each providing 1.4 mg quercetin/kg. Follow-up or treatment period: Single-dose comparisons.

The aglycone-rich dried skin preparation produced higher plasma exposure than the glucoside-rich flesh preparation.

Food matrix and preparation differed alongside chemical form. Results cannot establish that purified aglycone always outperforms glucosides.

Continue with Quercetin Data Center

For topic-level interpretation, read Foods High in Quercetin: Practical Sources and Portions. This is a related guide; the citation panel separately identifies articles that directly cite this paper.

Key findings

  • The aglycone-rich dried skin preparation produced higher plasma exposure than the glucoside-rich flesh preparation.
  • The recorded outcome domains were Exposure and pharmacokinetics.
  • The result applies to the tested exposure: Shallot flesh or dried shallot skin, each providing 1.4 mg quercetin/kg; Single-dose comparisons.

What this study can and cannot tell us

  • Food matrix and preparation differed alongside chemical form. Results cannot establish that purified aglycone always outperforms glucosides.
  • 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.

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Editorial review

Reviewed by the Biohack Blueprint research team

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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