Outcome
    Moderate Evidence

    Vitamin C for Oxidative Damage Repair

    Vitamin C corrects deficiency and supports plasma antioxidant capacity, but high doses around training blunt adaptation.

    Overview

    Vitamin C corrects deficiency and supports plasma antioxidant capacity, but high doses around training blunt adaptation.

    Verdict

    Mixed evidence

    How It Works

    Ascorbate is a water-soluble radical scavenger and regenerates vitamin E. At supraphysiological doses it suppresses the exercise-induced ROS signalling that triggers mitochondrial biogenesis.

    Dosing & Protocol

    Typical dose

    Recommended dose
    Food-first; supplement 200-500mg/day if intake is low, away from training
    Expected timeframe
    4-8 weeks

    Protocol

    form
    Ascorbic acid, or buffered ascorbate if stomach upset occurs
    duration
    4-12 weeks
    co factor
    Take with food in divided doses. Evidence is mixed. Vitamin C is the principal water-soluble antioxidant in plasma, regenerates vitamin E, and reduces markers of oxidative damage such as F2-isoprostanes and 8-OHdG in some trials - particularly in smokers, people with diabetes and those with low baseline status. Other trials find no effect, and vitamin C can act as a pro-oxidant in the presence of free transition metals, particularly iron, which is why high doses in iron overload are cautioned against. Damage repair as such is not measured - what is measured is the level of oxidised molecules at a point in time.
    titration
    Up to 1,000 mg/day in divided doses; the tolerable upper intake level is 2,000 mg/day
    starting dose
    500 mg/day with food

    Evidence

    What the studies say

    Deficiency correction clearly improves oxidative markers. Trials of 1000mg/day alongside endurance training show attenuated VO2max and mitochondrial gains, and prevention trials in well-nourished populations are null.

    Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases

    Score: 9/10
    2012
    meta_analysis
    n=296707

    Bjelakovic G, Nikolova D, Gluud LL +2 more

    vitamin C (3637 dead/36,659 (9.9%) versus 2717 dead/29,283 (9.3%); 29 trials, RR 1.02, 95% CI 0.98 to 1.07)

    View source

    Safety

    Caveats

    Doses above 1000mg/day increase oxalate kidney stone risk in susceptible people and cause GI upset.

    Less likely to help if

    People with adequate vitamin C status and low oxidative burden.

    Medical Disclaimer

    The information provided on this website is for educational and informational purposes only and is not intended as a substitute for professional medical advice, diagnosis, or treatment. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition or before starting any supplement regimen.

    Individual results may vary. The statements on this website have not been evaluated by the Food and Drug Administration. Products and information are not intended to diagnose, treat, cure, or prevent any disease.