title: Low vitamin C values are linked with decreased physical performance and increased oxidative stress: reversal by vitamin C supplementation.
abstract: OBJECTIVE
  It has been suggested that part of the failure of antioxidant supplementation to reduce oxidative stress and promote health is that it has been administered in humans with normal levels of antioxidants.
  
  
  METHODS
  To test this hypothesis, we screened 100 males for vitamin C baseline values in blood. Subsequently, the 10 individuals with the lowest and the 10 with the highest vitamin C values were assigned in two groups. Using a placebo-controlled crossover design, the 20 selected subjects performed aerobic exercise to exhaustion (oxidant stimulus) before and after vitamin C supplementation for 30 days.
  
  
  RESULTS
  The low vitamin C group had lower VO2max values than the high vitamin C group. Vitamin C supplementation in this group marginally increased VO2max. Baseline concentration of F2-isoprostanes and protein carbonyls was higher in the low vitamin C group compared to the high vitamin C group. Vitamin C supplementation decreased the baseline concentration of F2-isoprostanes and protein carbonyls in both groups, yet the decrease was greater in the low vitamin C group. Before vitamin C supplementation, F2-isoprostanes and protein carbonyls were increased to a greater extent after exercise in the high vitamin C group compared to the low vitamin C group. Interestingly, after vitamin C supplementation, this difference was narrowed.
  
  
  CONCLUSIONS
  We show for the first time that low vitamin C concentration is linked with decreased physical performance and increased oxidative stress and that vitamin C supplementation decreases oxidative stress and might increase exercise performance only in those with low initial concentration of vitamin C.
authors.affiliation: School of Physical Education and Sport Science, University of Thessaly, 42100, Karies, Trikala, Greece.|Department of Health Sciences, School of Sciences, European University Cyprus, Nicosia, Cyprus.
authors.forename: Vassilis
authors.initials: V
authors.lastname: Paschalis
authors.affiliation: Department of Health Sciences, School of Sciences, European University Cyprus, Nicosia, Cyprus.
authors.forename: Anastasios A
authors.initials: AA
authors.lastname: Theodorou
authors.affiliation: School of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, 62110, Agios Ioannis, Serres, Greece.
authors.forename: Antonios
authors.initials: A
authors.lastname: Kyparos
authors.affiliation: School of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, 62110, Agios Ioannis, Serres, Greece.
authors.forename: Konstantina
authors.initials: K
authors.lastname: Dipla
authors.affiliation: School of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, 62110, Agios Ioannis, Serres, Greece.
authors.forename: Andreas
authors.initials: A
authors.lastname: Zafeiridis
authors.affiliation: Department of Health Sciences, School of Sciences, European University Cyprus, Nicosia, Cyprus.
authors.forename: George
authors.initials: G
authors.lastname: Panayiotou
authors.affiliation: School of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, 62110, Agios Ioannis, Serres, Greece.
authors.forename: Ioannis S
authors.initials: IS
authors.lastname: Vrabas
authors.affiliation: School of Physical Education and Sports Science at Serres, Aristotle University of Thessaloniki, 62110, Agios Ioannis, Serres, Greece. nikolaidis@auth.gr.
authors.forename: Michalis G
authors.initials: MG
authors.lastname: Nikolaidis
mesh_terms: D000975:Antioxidants / Q000008:administration & dosage; D001205:Ascorbic Acid / Q000008:administration & dosage* / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D018592:Cross-Over Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage; D004041:Dietary Fats / Q000008:administration & dosage; D004044:Dietary Proteins / Q000008:administration & dosage; D019587:Dietary Supplements; D004311:Double-Blind Method; D002149:Energy Intake; D015444:Exercise; D028441:F2-Isoprostanes / Q000097:blood; D006801:Humans; D008297:Male; D018384:Oxidative Stress / Q000187:drug effects*; D010101:Oxygen Consumption / Q000187:drug effects; D055815:Young Adult
chemical_list: D000975:Antioxidants; D015415:Biomarkers; D004040:Dietary Carbohydrates; D004041:Dietary Fats; D004044:Dietary Proteins; D028441:F2-Isoprostanes; D001205:Ascorbic Acid
keywords: Antioxidants; Exercise; Oxidative stress; Physical performance; Supplementation