Tier 2 — strong

Effects of a quercetin-rich onion skin extract on 24 h ambulatory blood pressure and endothelial function in overweight-to-obese patients with (pre-)hypertension: a randomised double-blinded placebo-controlled cross-over trial

Verena Brüll, Constanze Burak, Birgit Stoffel-Wagner, Siegfried Wolffram, Georg Nickenig, Cornelius Müller, Peter Langguth, Birgit Alteheld, Rolf Fimmers, Stefanie Naaf, Benno F Zimmermann, Peter Stehle, Sarah Egert
The British journal of nutrition 2015 114(8):1263

Bibliography

PubMed
PMID 26328470
PubMed Central
PMC4594049
DOI
10.1017/S0007114515002950
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 crossover trial
ModelHuman intervention research
Sample70 adults with prehypertension or stage 1 hypertension
InterventionOnion-skin extract providing quercetin 162 mg/day versus placebo
Duration6-week periods with 6-week washout
EndpointsBlood pressure

What the study showed, in plain terms

Published in 2015, this source examined cardiovascular and metabolic health. Design: Randomized double-blind placebo-controlled crossover trial. Sample/model: 70 adults with prehypertension or stage 1 hypertension. The exposure or intervention was Onion-skin extract providing quercetin 162 mg/day versus placebo. Follow-up or treatment period: 6-week periods with 6-week washout.

Overall blood-pressure outcomes were null. A hypertensive subgroup showed a modest reduction in 24-hour systolic pressure.

Subgroup results and a specific extract limit generalization. Other vascular and metabolic biomarkers did not improve.

Continue with Quercetin Data Center

For topic-level interpretation, read Quercetin and Blood Pressure: How Large Is the Effect?. This is a related guide; the citation panel separately identifies articles that directly cite this paper.

Key findings

  • Overall blood-pressure outcomes were null.
  • A hypertensive subgroup showed a modest reduction in 24-hour systolic pressure.
  • The recorded outcome domains were Blood pressure.
  • The result applies to the tested exposure: Onion-skin extract providing quercetin 162 mg/day versus placebo; 6-week periods with 6-week washout.

What this study can and cannot tell us

  • Subgroup results and a specific extract limit generalization. Other vascular and metabolic biomarkers did not improve.
  • 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: accessible full text and indexed metadata. Missing method details, funding information or participant denominators are not inferred.

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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