Tier 2 — strong

No effects of quercetin from onion skin extract on serum leptin and adiponectin concentrations in overweight-to-obese patients with (pre-)hypertension: a randomized double-blinded, placebo-controlled crossover trial

Verena Brüll, Constanze Burak, Birgit Stoffel-Wagner, Siegfried Wolffram, Georg Nickenig, Cornelius Müller, Peter Langguth, Birgit Alteheld, Rolf Fimmers, Peter Stehle, Sarah Egert
European journal of nutrition 2017 56(7):2265

Bibliography

PubMed
PMID 27423432
DOI
10.1007/s00394-016-1267-0
Funding
Indexed grant support: EG292/3-1 — Deutsche Forschungsgemeinschaft — United States. The indexed list may not contain the complete funding declaration.
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 randomized adults; 68 analyzed
InterventionOnion-skin extract providing quercetin 162 mg/day versus placebo
Duration6-week periods separated by 6-week washout
EndpointsGlucose and insulin measures; Inflammatory measures

What the study showed, in plain terms

Published in 2017, this source examined cardiovascular and metabolic health. Design: Randomized double-blind placebo-controlled crossover trial. Sample/model: 70 randomized adults; 68 analyzed. The exposure or intervention was Onion-skin extract providing quercetin 162 mg/day versus placebo. Follow-up or treatment period: 6-week periods separated by 6-week washout.

Leptin, adiponectin, inflammatory markers, glucose and insulin did not improve. Measured short-term safety markers did not change.

Companion report from the onion-extract pressure trial. No general anti-inflammatory or insulin-sensitizing benefit was demonstrated.

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

  • Leptin, adiponectin, inflammatory markers, glucose and insulin did not improve.
  • Measured short-term safety markers did not change.
  • The recorded outcome domains were Glucose and insulin measures; Inflammatory measures.
  • The result applies to the tested exposure: Onion-skin extract providing quercetin 162 mg/day versus placebo; 6-week periods separated by 6-week washout.

What this study can and cannot tell us

  • Companion report from the onion-extract pressure trial. No general anti-inflammatory or insulin-sensitizing benefit was demonstrated.
  • 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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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