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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

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European Journal of Nutrition Aims and scope Submit manuscript

Abstract

Purpose

Chronic low-level systemic and adipose tissue inflammation has been identified as a major etiologic factor in many chronic diseases, including hypertension and cardiovascular diseases. Evidence from experimental studies suggests anti-inflammatory effects of dietary flavonols such as quercetin.

Methods

We investigated the effects of regular intake of quercetin on leptin, adiponectin, biomarkers of inflammation, glucose and insulin in overweight-to-obese patients with pre- and stage 1 hypertension. Another objective was to assess the safety of daily quercetin supplementation measured by parameters of liver and kidney function and of hematology. Subjects (n = 70) were randomized to receive a supra-nutritional dose of 162 mg/d quercetin or placebo in a double-blinded, placebo-controlled crossover trial with 6-week treatment periods separated by a 6-week washout period. Two subjects dropped out for personal reasons. Only data from the remaining 68 subjects were included in the analysis.

Results

Compared to placebo, quercetin did not significantly affect serum concentrations of leptin and adiponectin, HOMA-AD or the ratios of leptin/adiponectin and adiponectin/leptin. Neither quercetin nor placebo significantly changed serum C-reactive protein and plasma tumor necrosis factor alpha. Compared to placebo, quercetin did not significantly affect glucose, insulin, HOMA-IR, blood biomarkers of liver and renal function, hematology and serum electrolytes.

Conclusion

A supra-nutritional dose of 162 mg/d quercetin from onion skin extract for 6 weeks is safe but without significant effects on parameters of systemic and adipose tissue inflammation as well as glucose and insulin in overweight-to-obese subjects with (pre-)hypertension. This trial was registered at www.germanctr.de/ and http://apps.who.int/trialsearch/ as DRKS00000555.

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Abbreviations

ALT:

Alanine transaminase

AST:

Aspartate transaminase

CVD:

Cardiovascular diseases

CRP:

C-reactive protein

GGT:

Gamma-glutamyl transpeptidase

hs:

High sensitive

HOMA-AD:

Homeostasis model assessment-adiponectin

HOMA-IR:

Homeostasis model assessment of insulin resistance

IL:

Interleukin

RM-ANOVA:

Repeated-measures ANOVA

TNFα:

Tumor necrosis factor alpha

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Acknowledgments

The authors are indebted to our volunteers for their interest and participation in our study; to Rudolf Wild GmbH & Company KG (Matthias Saß) for the supply of the onion skin extract; to Petra Pickert, Margret Schüller, Christel Bierschbach, Adelheid Schuch, Anke Ernst, Petra Schulz, Anke Carstensen and Ute Hartung for excellent technical assistance; and to Sarah Krönung, Elvis Kolobara, Claudia Pagliarucci, Lisa Albrecht, Ramona Napp and Michael Napp for performing the venipunctures. This study was supported by Grant No. EG292/3-1 of the German Research Foundation (to SE).

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Authors and Affiliations

  1. Department of Nutrition and Food Sciences, Nutritional Physiology, University of Bonn, Endenicher Allee 11-13, 53115, Bonn, Germany

    Verena Brüll, Constanze Burak, Birgit Alteheld, Peter Stehle & Sarah Egert

  2. Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany

    Birgit Stoffel-Wagner

  3. Institute of Animal Nutrition and Physiology, Christian-Albrechts-University Kiel, Kiel, Germany

    Siegfried Wolffram

  4. Department of Cardiology, Angiology and Pneumology, University Hospital Bonn, Bonn, Germany

    Georg Nickenig & Cornelius Müller

  5. Institute of Pharmacy and Biochemistry, Department of Biopharmaceutics and Pharmaceutical Technology, Johannes Gutenberg University Mainz, Mainz, Germany

    Peter Langguth

  6. Institute of Medical Biometry, Informatics and Epidemiology, University Hospital Bonn, Bonn, Germany

    Rolf Fimmers

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  1. Verena Brüll
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  2. Constanze Burak
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  6. Cornelius Müller
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  7. Peter Langguth
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  9. Rolf Fimmers
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  10. Peter Stehle
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  11. Sarah Egert
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Correspondence to Sarah Egert.

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Ethical standards

The study was conducted according to the guidelines laid down in the 1964 Declaration of Helsinki, and its later amendments and all procedures involving human participants were approved by the ethical committee of the Medical Faculty of the Rheinische Friedrich-Wilhelms-Universität Bonn, Germany. Written informed consent was obtained from all participants.

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Brüll, V., Burak, C., Stoffel-Wagner, B. et al. 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. Eur J Nutr 56, 2265–2275 (2017). https://doi.org/10.1007/s00394-016-1267-0

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