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Medical AI Inquiry: You was designed to assist in medical decision-making based on the provided user questions. It is crucial to provide accurate and comprehensive information to receive a well-informed response.  Labels: OBJECTIVE, METHODS, RESULTS. Meshes: Adult, Antioxidants, Ascorbic Acid, Cross-Over Studies, Dose-Response Relationship, Drug, Fasting, Free Radical Scavengers, Free Radicals, Guanosine, Humans, Infusions, Intravenous, Male, Oxidation-Reduction, Oxidative Stress, Prospective Studies, Reactive Oxygen Species, Thiobarbituric Acid Reactive Substances.
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Is high-dose intravenous vitamin C associated with an increase of pro-oxidative biomarkers? Context: High-dose vitamin C therapy might mediate beneficial clinical effects by counteracting reactive oxygen species. However, concerns are raised whether this approach might provoke diametrical (ie pro-oxidative) effects. The objective was to determine ascorbyl free radical (AFR) concentrations and potential variables of pro-oxidative damage. Crossover study; six healthy males received daily infusions of 750 or 7500 mg vitamin C for six consecutive days. Fasting concentrations of vitamin C and AFR were determined daily. On day 1, concentrations of vitamin C and AFR were measured at 0.25, 0.5, 1, 2, 4 and 8 h post infusion. Plasma concentrations of thiobarbituric acid-reactive substances (TBARS), tocopherol and urine concentrations of 8-oxoguanosine were determined on days 1 and 6. Kinetic studies on day 1 showed that concentrations of vitamin C and AFR displayed parallel dose- and time-dependent kinetics and elimination was highly efficient. Vitamin C and AFR fasting concentrations on days 2-6 were slightly above the baseline, suggesting new, stable steady states. TBARS decreased in both groups, whereas tocopherol and 8-oxoguanosine concentrations remained unchanged.
assistant
Kinetics of AFR largely depend on plasma vitamin C concentrations and AFR is eliminated efficiently. Our data do not support induction of pro-oxidative effects in healthy volunteers given intravenous high-dose vitamin C. Final Decision: no