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- Title
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.
- Authors
Brüll, Verena; Burak, Constanze; Stoffel-Wagner, Birgit; Wolffram, Siegfried; Nickenig, Georg; Müller, Cornelius; Langguth, Peter; Alteheld, Birgit; Fimmers, Rolf; Stehle, Peter; Egert, Sarah
- 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 and as DRKS00000555.
- Subjects
BIOMARKERS; BLOOD sugar; CROSSOVER trials; DIETARY supplements; INFLAMMATION; INSULIN; OBESITY; ONIONS; QUERCETIN; STATISTICAL sampling; LEPTIN; PLANT extracts; RANDOMIZED controlled trials; BLIND experiment; ADIPONECTIN; PREHYPERTENSION
- Publication
European Journal of Nutrition, 2017, Vol 56, Issue 7, p2265
- ISSN
1436-6207
- Publication type
Article
- DOI
10.1007/s00394-016-1267-0