title: Oxidative stress is associated with an increased antioxidant defense in elderly subjects: a multilevel approach.
abstract: BACKGROUND
  Studies of associations between plasma GSH-Px activity and cardiovascular risk factors have been done in humans, and contradictory results have been reported. The aim of our study was to assess the association between the scavenger antioxidant enzyme glutathione peroxidase (GSH-Px) activity in plasma and the presence of novel and classical cardiovascular risk factors in elderly patients.
  
  
  METHODS
  We performed a cross-sectional study with baseline data from a subsample of the PREDIMED (PREvención con DIeta MEDiterránea) study in Spain. Participants were 1,060 asymptomatic subjects at high risk for cardiovascular disease (CVD), aged 55 to 80, selected from 8 primary health care centers (PHCCs). We assessed classical CVD risk factors, plasma oxidized low-density lipoproteins (ox-LDL), and glutathione peroxidase (GSH-Px) using multilevel statistical procedures.
  
  
  RESULTS
  Mean GSH-Px value was 612 U/L (SE: 12 U/L), with variation between PHCCs ranging from 549 to 674 U/L (Variance =  013.5; P<0.001). Between-participants variability within a PHCC accounted for 89% of the total variation. Both glucose and oxidized LDL were positively associated with GSH-Px activity after adjustment for possible confounder variables (P = 0.03 and P = 0.01, respectively).
  
  
  CONCLUSIONS
  In a population at high cardiovascular risk, a positive linear association was observed between plasma GSH-Px activity and both glucose and ox-LDL levels. The high GSH-Px activity observed when an oxidative stress situation occurred, such as hyperglycemia and lipid oxidative damage, could be interpreted as a healthy defensive response against oxidative injury in our cardiovascular risk population.
authors.affiliation: Unitat de Suport a la Recerca Tarragona-Reus, Institut Universitari d'Investigació en Atenció Primària Jordi Gol (IDIAP Jordi Gol), Tarragona, Spain; CIBER Fisiopatología Obesidad y Nutrición (CIBEROBN), Madrid, Spain.
authors.forename: Gemma
authors.initials: G
authors.lastname: Flores-Mateo
authors.affiliation: Epidemiology and Cardiovascular Genetics Research Group, Institut Municipal d'Investigació Mèdica (IMIM), Barcelona, Spain; CIBER de Epidemiología y Salud Pública (CIBERESP), Madrid, Spain.
authors.forename: Roberto
authors.initials: R
authors.lastname: Elosua
authors.affiliation: Institut Universitari d'Investigació en Atenció Primària Jordi Gol (IDIAP Jordi Gol), Barcelona, Spain.
authors.forename: Teresa
authors.initials: T
authors.lastname: Rodriguez-Blanco
authors.affiliation: Unitat de Suport a la Recerca Tarragona-Reus, Institut Universitari d'Investigació en Atenció Primària Jordi Gol (IDIAP Jordi Gol), Tarragona, Spain; CIBER Fisiopatología Obesidad y Nutrición (CIBEROBN), Madrid, Spain.
authors.forename: Josep
authors.initials: J
authors.lastname: Basora-Gallisà
authors.affiliation: CIBER Fisiopatología Obesidad y Nutrición (CIBEROBN), Madrid, Spain; Human Nutrition Unit, School of Medicine, University Rovira i Virgili, Reus, Spain.
authors.forename: Mònica
authors.initials: M
authors.lastname: Bulló
authors.affiliation: CIBER Fisiopatología Obesidad y Nutrición (CIBEROBN), Madrid, Spain; Human Nutrition Unit, School of Medicine, University Rovira i Virgili, Reus, Spain.
authors.forename: Jordi
authors.initials: J
authors.lastname: Salas-Salvadó
authors.affiliation: Department of Preventive Medicine and Public Health, University of Navarra-Osasunbidea, Servicio Navarro de Salud, Pamplona, Spain.
authors.forename: Miguel Ángel
authors.initials: MÁ
authors.lastname: Martínez-González
authors.affiliation: CIBER Fisiopatología Obesidad y Nutrición (CIBEROBN), Madrid, Spain; Department of Internal Medicine, Hospital Clinic, Institut dInvestigacions Biomèdiques August Pi Sunyer (IDIBAPS), Barcelona, Spain.
authors.forename: Ramon
authors.initials: R
authors.lastname: Estruch
authors.affiliation: CIBER Fisiopatología Obesidad y Nutrición (CIBEROBN), Madrid, Spain; Department of Preventive Medicine and Public Health, University of Valencia, Valencia, Spain.
authors.forename: Dolores
authors.initials: D
authors.lastname: Corella
authors.affiliation: CIBER Fisiopatología Obesidad y Nutrición (CIBEROBN), Madrid, Spain; Cardiovascular Risk and Nutrition Research Unit, Institut Municipal d'Investigació Mèdica (IMIM), Barcelona, Spain.
authors.forename: Montserrat
authors.initials: M
authors.lastname: Fitó
authors.affiliation: CIBER Fisiopatología Obesidad y Nutrición (CIBEROBN), Madrid, Spain; Institute for Health Sciences Investigation, IdISPa, Palma de Mallorca, Spain.
authors.forename: Miquel
authors.initials: M
authors.lastname: Fiol
authors.affiliation: Department of Cardiology, Hospital Txangorritxu, Vitoria, Spain.
authors.forename: Fernando
authors.initials: F
authors.lastname: Arós
authors.affiliation: Department of Epidemiology, School of Medicine of Malaga, Malaga, Spain.
authors.forename: Enrique
authors.initials: E
authors.lastname: Gómez-Gracia
authors.affiliation: CIBER de Epidemiología y Salud Pública (CIBERESP), Madrid, Spain; Institut Universitari d'Investigació en Atenció Primària Jordi Gol (IDIAP Jordi Gol), Barcelona, Spain.
authors.forename: Isaac
authors.initials: I
authors.lastname: Subirana
authors.affiliation: Department of Family Medicine, Primary Care Division of Sevilla, San Pablo Health Center, Sevilla, Spain.
authors.forename: José
authors.initials: J
authors.lastname: Lapetra
authors.affiliation: CIBER Fisiopatología Obesidad y Nutrición (CIBEROBN), Madrid, Spain; Instituto de la Grasa, CSIC, Sevilla, Spain.
authors.forename: Valentina
authors.initials: V
authors.lastname: Ruiz-Gutiérrez
authors.affiliation: CIBER Fisiopatología Obesidad y Nutrición (CIBEROBN), Madrid, Spain; Department of Biochemistry and Molecular Biology, Faculty of Medicine, Service of Clinical Analysis, Doctor Peset University Hospital, University of Valencia, Valencia, Spain.
authors.forename: Guillermo T
authors.initials: GT
authors.lastname: Sáez
authors.affiliation: CIBER Fisiopatología Obesidad y Nutrición (CIBEROBN), Madrid, Spain; CIBER Fisiopatología Obesidad y Nutrición (CIBEROBN), Madrid, Spain; Cardiovascular Risk and Nutrition Research Unit, Institut Municipal d'Investigació Mèdica (IMIM), Barcelona, Spain.
authors.forename: Maria-Isabel
authors.initials: MI
authors.lastname: Covas
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D000975:Antioxidants / Q000378:metabolism; D003430:Cross-Sectional Studies; D005260:Female; D005979:Glutathione Peroxidase / Q000097:blood*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D018384:Oxidative Stress; D012044:Regression Analysis
chemical_list: D000975:Antioxidants; D005979:Glutathione Peroxidase