title: Antioxidant supplementation does not attenuate oxidative stress at high altitude.
abstract: BACKGROUND
  Hypobaric hypoxia and heightened metabolic rate increase free radical production.
  
  
  OBJECTIVE
  We tested the hypothesis that antioxidant supplementation would reduce oxidative stress associated with increased energy expenditure (negative energy balance) at high altitude (HA 4300 m).
  
  
  METHODS
  For 12 d at sea level (SL), 18 active men were fed a weight-stabilizing diet. Testing included fasting blood and 24-h urine samples to assess antioxidant status [plasma alpha-tocopherol, beta-carotene, lipid hydroperoxides (LPO), and urinary 8-hydroxydeoxyguanosine (8-OHdG)] and a prolonged submaximal (55% Vo2peak) oxidative stress index test (OSI) to evaluate exercise-induced oxidative stress (plasma LPO, whole blood reduced and oxidized glutathione, glutathione peroxidase, and urinary 8-OHdG). Subjects were then matched and randomly assigned to either a placebo or antioxidant supplement group for a double-blinded trial. Supplementation (20,000 IU of beta-carotene, 400 IU alpha-tocopherol acetate, 500 mg ascorbic acid, 100 microg selenium, and 30 mg zinc, or placebo) was begun 3 wk prior to and throughout a 14-d HA intervention. At HA, subjects' daily energy intake and expenditure were adjusted to achieve a caloric deficit of approximately 1400 kcal. Fasting blood and 24-h urine samples were collected throughout HA and the OSI test was repeated on HA day 1 and day 13.
  
  
  RESULTS
  Resting LPO concentrations increased and urinary 8-OHdG concentrations decreased over HA with no effect of supplementation. Prolonged submaximal exercise was not associated with increased concentrations of oxidative stress markers at SL or HA.
  
  
  CONCLUSIONS
  Antioxidant supplementation did not significantly affect markers of oxidative stress associated with increased energy expenditure at HA.
authors.affiliation: VA Palo Alto Health Care System, 3801 Miranda Ave., Palo Alto, CA 94304-1290, USA.
authors.forename: Andrew W
authors.initials: AW
authors.lastname: Subudhi
authors.forename: Kevin A
authors.initials: KA
authors.lastname: Jacobs
authors.forename: Todd A
authors.initials: TA
authors.lastname: Hagobian
authors.forename: Jill A
authors.initials: JA
authors.lastname: Fattor
authors.forename: Charles S
authors.initials: CS
authors.lastname: Fulco
authors.forename: Stephen R
authors.initials: SR
authors.lastname: Muza
authors.forename: Paul B
authors.initials: PB
authors.lastname: Rock
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Hoffman
authors.forename: Allen
authors.initials: A
authors.lastname: Cymerman
authors.forename: Anne L
authors.initials: AL
authors.lastname: Friedlander
mesh_terms: D000328:Adult; D000532:Altitude Sickness / Q000503:physiopathology* / Q000517:prevention & control*; D000975:Antioxidants / Q000494:pharmacology* / Q000627:therapeutic use; D004249:DNA Damage; D004032:Diet; D004311:Double-Blind Method; D015444:Exercise / Q000502:physiology*; D006801:Humans; D015227:Lipid Peroxidation; D008297:Male; D018384:Oxidative Stress; D010919:Placebos
chemical_list: D000975:Antioxidants; D010919:Placebos