British Journal of Nutrition

Full Papers

Human and Clinical Nutrition

Quercetin reduces systolic blood pressure and plasma oxidised low-density lipoprotein concentrations in overweight subjects with a high-cardiovascular disease risk phenotype: a double-blinded, placebo-controlled cross-over study

Sarah Egerta1, Anja Bosy-Westphala1, Jasmin Seiberla1, Claudia Kürbitza1, Uta Settlera1, Sandra Plachta-Danielzika1, Anika E. Wagnera2, Jan Franka2, Jürgen Schrezenmeira3, Gerald Rimbacha2, Siegfried Wolfframa4 and Manfred J. Müllera1 c1

a1 Institute of Human Nutrition and Food Science, Department of Human Nutrition, Christian-Albrechts-University Kiel, 24105 Kiel, Germany

a2 Institute of Human Nutrition and Food Science, Department of Food Science, Christian-Albrechts-University Kiel, 24118 Kiel, Germany

a3 Max Rubner-Institute, Federal Research Institute of Nutrition and Food, 24103 Kiel, Germany

a4 Institute of Animal Nutrition, Physiology and Metabolism, Christian-Albrechts-University Kiel, 24118 Kiel, Germany


Regular consumption of flavonoids may reduce the risk for CVD. However, the effects of individual flavonoids, for example, quercetin, remain unclear. The present study was undertaken to examine the effects of quercetin supplementation on blood pressure, lipid metabolism, markers of oxidative stress, inflammation, and body composition in an at-risk population of ninety-three overweight or obese subjects aged 25–65 years with metabolic syndrome traits. Subjects were randomised to receive 150 mg quercetin/d in a double-blinded, placebo-controlled cross-over trial with 6-week treatment periods separated by a 5-week washout period. Mean fasting plasma quercetin concentrations increased from 71 to 269 nmol/l (P < 0·001) during quercetin treatment. In contrast to placebo, quercetin decreased systolic blood pressure (SBP) by 2·6 mmHg (P < 0·01) in the entire study group, by 2·9 mmHg (P < 0·01) in the subgroup of hypertensive subjects and by 3·7 mmHg (P < 0·001) in the subgroup of younger adults aged 25–50 years. Quercetin decreased serum HDL-cholesterol concentrations (P < 0·001), while total cholesterol, TAG and the LDL:HDL-cholesterol and TAG:HDL-cholesterol ratios were unaltered. Quercetin significantly decreased plasma concentrations of atherogenic oxidised LDL, but did not affect TNF-α and C-reactive protein when compared with placebo. Quercetin supplementation had no effects on nutritional status. Blood parameters of liver and kidney function, haematology and serum electrolytes did not reveal any adverse effects of quercetin. In conclusion, quercetin reduced SBP and plasma oxidised LDL concentrations in overweight subjects with a high-CVD risk phenotype. Our findings provide further evidence that quercetin may provide protection against CVD.

(Received January 26 2009)

(Revised March 25 2009)

(Accepted March 27 2009)

(Online publication April 30 2009)


c1 Corresponding author: Professor Manfred James Müller, fax +49 431 8805679, email


Abbreviations: CRP, C-reactive protein; DBP, diastolic blood pressure; hs, high-sensitivity; SBP, systolic blood pressure