title: Acute intake of quercetin from onion skin extract does not influence postprandial blood pressure and endothelial function in overweight-to-obese adults with hypertension: a randomized, double-blind, placebo-controlled, crossover trial.
abstract: OBJECTIVE
  To determine whether postprandial metabolic and vascular responses induced by a high-fat and high-carbohydrate meal are attenuated by ingestion of the flavonol quercetin.
  
  
  METHODS
  Twenty-two overweight-to-obese hypertensive patients participated in a randomized, double-blind, controlled, crossover meal study. They consumed a test meal (challenge) rich in energy (4754 kJ), fat (61.6 g), saturated fatty acids (53 % of total fatty acids), and carbohydrates (113.3 g) with either placebo or 54 mg quercetin. Blood pressure, reactive hyperemia index (RHI), high-sensitive C-reactive protein (hs-CRP), soluble endothelial-derived adhesion molecules, parameters of lipid and glucose metabolism, and markers of antioxidant status were measured before the meal and at 2 and 4 h postprandially.
  
  
  RESULTS
  Systolic and diastolic blood pressure increased significantly over time, but were not affected by treatment (placebo or quercetin). During both treatments, serum endothelin-1, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and plasma asymmetric dimethylarginine slightly decreased over time, whereas RHI increased. Serum triglycerides, total cholesterol, and insulin significantly increased, whereas HDL cholesterol and glucose significantly decreased over time, again with no effect of treatment. Plasma α-tocopherol significantly increased, and plasma Trolox equivalent antioxidative capacity decreased over time. Serum hs-CRP, plasma retinol, and β-carotene did not significantly change during the trial.
  
  
  CONCLUSIONS
  In hypertensive patients, a high-energy meal did not lead to postprandial impairment of vascular endothelial function. Postprandial metabolic responses induced by the challenge, such as lipemia and insulinemia, were not attenuated by the concomitant ingestion of quercetin.
  
  
  BACKGROUND
  This trial was registered at www.germanctr.de/ and http://apps.who.int/trialsearch/ as DRKS00000555.
authors.affiliation: Department of Nutrition and Food Sciences, Nutritional Physiology, University of Bonn, Endenicher Allee 11-13, 53115, Bonn, Germany.
authors.forename: Verena
authors.initials: V
authors.lastname: Brüll
authors.affiliation: Department of Nutrition and Food Sciences, Nutritional Physiology, University of Bonn, Endenicher Allee 11-13, 53115, Bonn, Germany.
authors.forename: Constanze
authors.initials: C
authors.lastname: Burak
authors.affiliation: Institute of Clinical Chemistry and Clinical Pharmacology, University Hospital Bonn, Bonn, Germany.
authors.forename: Birgit
authors.initials: B
authors.lastname: Stoffel-Wagner
authors.affiliation: Institute of Animal Nutrition and Physiology, Christian-Albrechts-University Kiel, Kiel, Germany.
authors.forename: Siegfried
authors.initials: S
authors.lastname: Wolffram
authors.affiliation: Department of Cardiology, Angiology and Pneumology, University Hospital Bonn, Bonn, Germany.
authors.forename: Georg
authors.initials: G
authors.lastname: Nickenig
authors.affiliation: Department of Cardiology, Angiology and Pneumology, University Hospital Bonn, Bonn, Germany.
authors.forename: Cornelius
authors.initials: C
authors.lastname: Müller
authors.affiliation: Institute of Pharmacy and Biochemistry, Department of Biopharmaceutics and Pharmaceutical Technology, Johannes Gutenberg University, Mainz, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Langguth
authors.affiliation: Department of Nutrition and Food Sciences, Nutritional Physiology, University of Bonn, Endenicher Allee 11-13, 53115, Bonn, Germany.
authors.forename: Birgit
authors.initials: B
authors.lastname: Alteheld
authors.affiliation: Institute of Medical Biometry, Informatics and Epidemiology, University Hospital Bonn, Bonn, Germany.
authors.forename: Rolf
authors.initials: R
authors.lastname: Fimmers
authors.affiliation: Department of Nutrition and Food Sciences, Nutritional Physiology, University of Bonn, Endenicher Allee 11-13, 53115, Bonn, Germany.
authors.forename: Peter
authors.initials: P
authors.lastname: Stehle
authors.affiliation: Department of Nutrition and Food Sciences, Nutritional Physiology, University of Bonn, Endenicher Allee 11-13, 53115, Bonn, Germany. s.egert@uni-bonn.de.
authors.forename: Sarah
authors.initials: S
authors.lastname: Egert
mesh_terms: D000328:Adult; D000368:Aged; D001120:Arginine / Q000031:analogs & derivatives / Q000097:blood; D001794:Blood Pressure / Q000187:drug effects*; D002097:C-Reactive Protein / Q000378:metabolism; D002784:Cholesterol / Q000097:blood; D018592:Cross-Over Studies; D004311:Double-Blind Method; D019332:Endothelin-1 / Q000097:blood; D005260:Female; D006801:Humans; D006973:Hypertension / Q000097:blood* / Q000150:complications; D007328:Insulin / Q000097:blood; D018799:Intercellular Adhesion Molecule-1 / Q000097:blood; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000097:blood* / Q000150:complications; D019697:Onions / Q000737:chemistry; D050177:Overweight / Q000097:blood* / Q000150:complications; D010936:Plant Extracts / Q000008:administration & dosage*; D019518:Postprandial Period; D011794:Quercetin / Q000008:administration & dosage*; D014280:Triglycerides / Q000097:blood; D019010:Vascular Cell Adhesion Molecule-1 / Q000097:blood; D014801:Vitamin A / Q000097:blood; D019207:beta Carotene / Q000097:blood
chemical_list: D019332:Endothelin-1; D007328:Insulin; D010936:Plant Extracts; D014280:Triglycerides; D019010:Vascular Cell Adhesion Molecule-1; C487735:dimethylarginine; D019207:beta Carotene; D014801:Vitamin A; D018799:Intercellular Adhesion Molecule-1; D002097:C-Reactive Protein; D001120:Arginine; D002784:Cholesterol; D011794:Quercetin
keywords: Blood pressure; Cardiovascular diseases; Endothelial function; Postprandial metabolism; Quercetin