Onion consumption: relationship between intake and serum concentrations of quercetin and biomarkers of endothelial dysfunction in hypertensive subjects

Abstract

The consumption of quercetin, a polyphenol mostly present in onions, has beneficial antioxidants and anti-inflammatory properties in endothelial dysfunction (ED) in people with arterial hypertension (AH).

The objective was to study the correlation between onion consumption, serum quercetin concentration and the cardiometabolic risk factors through anthropometrical, biochemical and blood pressure markers in people suffering from AH.

Descriptive and correlational, cross sectional study. The number of volunteer subjects was 21, of both genders, between 35 and 70 years old, that went to the Cardiology Department in the National Clinic Hospital of Cordoba, Argentina, with their previous consent signature. The ingest of quercetin foods, physical activities and tobacco consumption were rated by validated surveys. Subsequently, anthropometrical, biochemical and blood pressure measurements were taken. Serum quercetin concentration was analyzed by using high performance liquid chromatography (HPLC). Nutrients and phytochemicals consumption was estimated with the Interfood software. Finally, the data was analyzed using the software Infostat, Stata v.11 and OriginPro8, applying test Wilcoxon, Fisher and Spearman.

According to the studies made to these 21 volunteers, 95,3% were overweighed, and, within this percentage, 90% showed central obesity. A high systolic blood pressure is present in 76% of the sample, while 47,6% has a high diastolic blood pressure, 60% hypercholesterolemia, 47.3% hypertriglyceridemia, 55% LDL cholesterol and altered glycaemia, and 94.7% shows risk values ​​for ultrasensitive C-reactive protein (PCRus). The average onion intake was 37.86 g / day ± 33.75 and that of quercetin was 8.65 mg / day ± 7.94. Serum quercetin concentrations showed no correlation with food source intake. A statistically significant direct association was noted between the PAD variable and the intake of onion and quercetin (r = 0.54; p = 0.01).

Although no correlation was found between onion consumption, quercetin concentrations and CRP levels, the sample shows risk factors for cardiometabolic diseases linked to inflammation