Effects of Onion Peel Extract on Endothelial Function

Effect of Onion Peel Extract on Endothelial Function and Endothelial Progenitor Cells in Overweight and Obese Subjects

Acute or chronic intake of polyphenol-rich foods has been reported to improve endothelial function. Quercetin, found abundantly in onion, is a potent antioxidant flavonoid. This study was designed to investigate whether consumption of onion peel extract (OPE) improves endothelial function in healthy overweight and obese subjects.

Epidemiological studies have shown a rapid increase in the prevalence of overweight and obesity, not only in adults but also in children and adolescents, thus increasing the risk of early development of cardiovascular disease (CVD). Quercetin, found abundantly in onion, prevents the induction of endothelial dysfunction, superoxide production, and overexpression by angiotensin II in the rat aorta. Furthermore, in our previous study we showed that supplementation with quercetin-rich onion peel extract (OPE) influenced adipokine expression, thus addressing its modulatory effect on obesity-induced inflammation, and improved insulin resistance by alleviating the metabolic dysregulation of free fatty acids, suppressing oxidative stress, upregulating glucose uptake, and downregulating inflammatory gene expression. But there are limited studies on the relationship between quercetin supplementation and endothelial dysfunction in humans.

After appropriate gating based on low cytoplasmic granularity and low expression of CD45, CD34+VEGFR2+ cells were counted and expressed as the number of cells/106 total events or number of cells/100 µL of blood.

Inclusion Criteria: age 20 to 60 years BMI >23 kg/m2 abdominal circumference > 90 cm in males or >85 cm in females Exclusion Criteria: hypertension (>140/90 mmHg), diabetes any cardiovascular disease, kidney disease, thyroid disease cerebrovascular disease liver disease (bilirubin level >2 mg/dl) pregnancy