title: Effect of onion peel extract on endothelial function and endothelial progenitor cells in overweight and obese individuals.
abstract: OBJECTIVE
  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. The aim of this study was to investigate whether consumption of onion peel extract (OPE) improves endothelial function in healthy overweight and obese individuals.
  
  
  METHODS
  This was a randomized double-blind, placebo-controlled study. Seventy-two healthy overweight and obese participants were randomly assigned to receive a red, soft capsule of OPE (100 mg quercetin/d, 50 mg quercetin twice daily; n = 36 participants) or an identical placebo capsule (n = 36) for 12 wk. Endothelial function, defined by flow-mediated dilation (FMD), circulating endothelial progenitor cells (EPCs) by flow cytometry, and laboratory test were determined at baseline and after treatment.
  
  
  RESULTS
  Baseline characteristics and laboratory findings did not significantly differ between the two groups. Compared with baseline values, the OPE group showed significantly improved FMD at 12 wk (from 12.5 ± 5.2 to 15.2 ± 6.1; P = 0.002), whereas the placebo group showed no difference. Nitroglycerin-mediated dilation did not change in either group. EPC counts (44.2 ± 25.6 versus 52.3 ± 18.6; P = 0.005) and the percentage of EPCs were significantly increased in the OPE group. When FMD was divided into quartiles, rate of patients with endothelial dysfunction defined as lowest quartile (cutoff value, 8.6%) of FMD improved from 26% to 9% by OPE.
  
  
  CONCLUSIONS
  Medium-term administration of OPE an improvement in FMD and circulating EPCs.
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Kyung Hee University College of Medicine, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Eun-Yong
authors.initials: EY
authors.lastname: Choi
authors.affiliation: Department of Medical Nutrition, Graduate School of East-West Medical Science, Kyung Hee University, Yongin 447-701, Republic of Korea; Research Institute of Medical Nutrition, Kyung Hee University, Seoul 130-701, Republic of Korea.
authors.forename: Hansongyi
authors.initials: H
authors.lastname: Lee
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Kyung Hee University College of Medicine, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Jong Shin
authors.initials: JS
authors.lastname: Woo
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Kyung Hee University College of Medicine, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Hyun Hee
authors.initials: HH
authors.lastname: Jang
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Kyung Hee University College of Medicine, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Seung Joon
authors.initials: SJ
authors.lastname: Hwang
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Kyung Hee University College of Medicine, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Hyun Soo
authors.initials: HS
authors.lastname: Kim
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Kyung Hee University College of Medicine, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Woo-Sik
authors.initials: WS
authors.lastname: Kim
authors.affiliation: Division of Endocrinology, Department of Internal Medicine, Kyung Hee University College of Medicine, Kyung Hee University, Seoul, Republic of Korea.
authors.forename: Young-Seol
authors.initials: YS
authors.lastname: Kim
authors.affiliation: Department of Medical Nutrition, Graduate School of East-West Medical Science, Kyung Hee University, Yongin 447-701, Republic of Korea; Research Institute of Medical Nutrition, Kyung Hee University, Seoul 130-701, Republic of Korea.
authors.forename: Ryowon
authors.initials: R
authors.lastname: Choue
authors.affiliation: Department of Food and Nutrition, Changwon National University, Changwon, Republic of Korea.
authors.forename: Yong-Jun
authors.initials: YJ
authors.lastname: Cha
authors.affiliation: Department of Food and Nutrition, Changwon National University, Changwon, Republic of Korea.
authors.forename: Jung-Eun
authors.initials: JE
authors.lastname: Yim
authors.affiliation: Division of Cardiology, Department of Internal Medicine, Kyung Hee University College of Medicine, Kyung Hee University, Seoul, Republic of Korea. Electronic address: mylovekw@hanmail.net.
authors.forename: Weon
authors.initials: W
authors.lastname: Kim
mesh_terms: D000328:Adult; D000975:Antioxidants / Q000494:pharmacology* / Q000627:therapeutic use; D002318:Cardiovascular Diseases / Q000517:prevention & control; D004311:Double-Blind Method; D066026:Endothelial Progenitor Cells / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000187:drug effects* / Q000503:physiopathology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D009765:Obesity / Q000188:drug therapy / Q000503:physiopathology*; D019697:Onions / Q000737:chemistry*; D008517:Phytotherapy; D010936:Plant Extracts / Q000494:pharmacology / Q000627:therapeutic use; D018517:Plant Roots / Q000737:chemistry; D059808:Polyphenols / Q000494:pharmacology / Q000627:therapeutic use; D011794:Quercetin / Q000494:pharmacology* / Q000627:therapeutic use; D014664:Vasodilation / Q000187:drug effects*
chemical_list: D000975:Antioxidants; D010936:Plant Extracts; D059808:Polyphenols; D011794:Quercetin
keywords: Endothelial function; Obesity; Onion peel extract; Quercetin