title: Influence of the placebo effect on oxidative stress in healthy older adults of Mexico City.
abstract: BACKGROUND
  The placebo effect has been widely recognized in the randomized clinical trials; nevertheless, this effect has not been evaluated in terms of antioxidant therapy on oxidative stress (OxS).
  
  
  OBJECTIVE
  The objective of this study was to determine the influence of the placebo effect on OxS in healthy older adults of Mexico City.
  
  
  METHODS
  We carried out a double-blind controlled clinical assay with the participation of 75 healthy older adults residents for the past 10 years of Mexico City; randomly distributed into three groups of 25 subjects each after previous informed consent; control group not received any treatment, placebo group received a placebo with a pharmaceutical presentation similar to that of the treatment, whereas treatment group were administered 1000 mg of ascorbic acid and 400 IU of alpha-tocopherol. All subjects ingested the treatment daily according to study group for 12 months. We measured before and after 12 months of treatment, lipoperoxides levels (LPO), erythrocyte superoxide dismutase, glutathione peroxidase and total plasma antioxidant status with Randox Laboratories Ltd kits. The concentration of ascorbic acid and alpha-tocopherol were measured using high-performance liquid chromatography.
  
  
  RESULTS
  The placebo group subjects showed a statistically significant decrease in LPO concentration, in the same way as the treatment group subjects (P < 0.01), both in comparison with a control group.
  
  
  CONCLUSIONS
  Our findings suggest that the placebo has a significant effect on OxS.
authors.affiliation: Unidad de Investigación en Gerontología, Facultad de Estudios Superiores Zaragoza, Universidad Nacional Autónoma de México (UNAM), México D.F.
authors.forename: R
authors.initials: R
authors.lastname: Retana-Ugalde
authors.forename: L A
authors.initials: LA
authors.lastname: Vargas
authors.forename: M
authors.initials: M
authors.lastname: Altamirano-Lozano
authors.forename: V M
authors.initials: VM
authors.lastname: Mendoza-Núñez
mesh_terms: D000368:Aged; D001205:Ascorbic Acid / Q000097:blood; D004311:Double-Blind Method; D005260:Female; D005979:Glutathione Peroxidase / Q000378:metabolism; D006801:Humans; D008054:Lipid Peroxides / Q000032:analysis; D008297:Male; D008875:Middle Aged; D018384:Oxidative Stress; D015990:Placebo Effect; D016032:Randomized Controlled Trials as Topic; D013482:Superoxide Dismutase / Q000378:metabolism; D014810:Vitamin E / Q000097:blood
chemical_list: D008054:Lipid Peroxides; D014810:Vitamin E; D005979:Glutathione Peroxidase; D013482:Superoxide Dismutase; D001205:Ascorbic Acid