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VITAMINS & SUPPLEMENTS · GUIDE

Antioxidants and Exercise: Performance, Recovery and Training Adaptation

What trials of vitamin C and E and other antioxidant supplements found for training adaptation, muscle soreness and performance, with conflicting results stated plainly.

Content last updated . This page has not been medically reviewed.

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Quick answer
Exercise makes the body produce reactive oxygen molecules, so it seems natural to think antioxidant supplements would help athletes recover. The trials do not support that simple idea. In the studies below, vitamin C and E together did not clearly improve results, and in some measures they blunted the body's response to training. [1][2] This page is information only, not a plan for any person. It covers supplements, not antioxidant-rich food.

What the trials found

5 findings · 3 mixed · 2 limited or unclearThe colour follows the evidence label on each card.

  1. Does vitamin C plus E change how well exercise improves insulin sensitivity?

    Mixed (small trial, a physiological measure rather than a disease outcome)

    In a 4-week trial of previously untrained (19) and pretrained (20) healthy young men, vitamin C 1000 mg/day plus vitamin E 400 IU/day (study amounts) was tested. [1] Insulin sensitivity rose with exercise only in the men who did not take the antioxidants. [1]

  2. Does vitamin C plus E change the muscle's response to endurance training?

    Mixed (biomarkers)

    A double-blind trial gave 54 young men and women vitamin C 1000 mg plus vitamin E 235 mg or placebo daily for 11 weeks (study amounts). [2] The supplement group's rise in muscle markers of mitochondrial growth was smaller. [2]

  3. Did that change fitness or running performance?

    No good evidence of a difference in these tests

    The same trial found no clear difference in the gain in maximal oxygen uptake or running performance. [2]

  4. Does it change the body's own antioxidant systems?

    Mixed

    In a related analysis of 37 participants given the same amounts, the authors report that C and E did not affect long-term training adaptations in the antioxidant and heat shock protein systems. [3]

  5. Does it reduce muscle soreness after hard exercise?

    No good evidence of meaningful benefit

    A Cochrane review included 50 placebo-controlled trials; it concluded high-dose antioxidant supplements do not cause a clinically relevant reduction in muscle soreness. [4]

Why the results look conflicting

The training-adaptation trials measured different things. One found a clear blunting of a body-response measure. [1] Another found blunted muscle markers but no difference in the performance tests it used. [2] A third found no effect on a different set of markers. [3] None of these shows that supplements make athletes slower or healthier, and none shows they help. The authors of the 11-week trial advised caution when combining antioxidant supplements with endurance exercise. [2]

NCCIH (US) explains one reason this may happen: large amounts of antioxidants may interfere with important functions in the cell, including its defense mechanisms and normal signaling. [5] For the wider idea that the body uses these molecules as signals, see antioxidants beyond neutralizing free radicals.

Related pages

Vitamin C and E are covered on vitamin C and vitamin E. Other uses are in antioxidant evidence by use, and recovery habits are in recovery after exercise.

Frequently asked questions

Do antioxidant supplements help muscles recover after exercise?

A Cochrane review of 50 placebo-controlled trials concluded that high-dose antioxidant supplements do not give a clinically relevant reduction in muscle soreness. [4]

Can vitamin C and E weaken the benefits of training?

In two trials using vitamin C and E together, some measures of the body's response to training were smaller in the supplement groups. [1][2] One of them found no difference in performance tests, so this is mixed evidence, not proof of harm. [2]

Do the trial amounts tell me what to take?

No. Those were study amounts in specific groups: 1000 mg vitamin C with 400 IU or 235 mg vitamin E. [1][2] They are not advice. A clinician or pharmacist can discuss what suits you.

Is antioxidant-rich food a problem for athletes too?

These trials tested supplements, not food, and the sources we read do not show that food has the same effect. NCCIH notes purified antioxidants may act differently than those consumed in foods. [5]

Are there safety concerns with high-dose antioxidants?

Yes. High-dose vitamin E may increase bleeding risk and interact with some medicines, and antioxidants may interfere with some cancer treatments. [5] Ask a clinician or pharmacist first.

More details: evidence, limits and cautions

The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.

How to read the evidence labels

Labels used on this page: mixed, no good evidence of benefit, evidence in adequately nourished people, insufficient evidence, "Proper evidence not found".

Limits of the soreness evidence
The Cochrane review also found:
  • Most participants were male (961 of 1089), with ages 16 to 55 in the trials. [4]
  • The majority of the trials (47) had design features that carried a high risk of bias. [4]
  • All studies used an antioxidant dosage higher than the recommended daily amount. [4]
  • None of the 50 trials measured subjective recovery. [4]
  • There was only limited evidence on adverse effects. [4]
Proper evidence not found
We looked in PubMed for systematic reviews of vitamin C and E supplements and endurance competition results in well-nourished athletes and did not find one we could read in full for this page. Proper evidence not found for a performance benefit of antioxidant supplements in competition, or for training adaptation in older adults, women-only samples or athletes with a diagnosed deficiency.
Safety and who should ask first

A clinician or pharmacist can say what suits a person. Nothing here is advice to start, stop or change a supplement or medicine.

References
  1. Ristow M, et al. Antioxidants prevent health-promoting effects of physical exercise in humans. Proc Natl Acad Sci U S A. 2009. Read 2026-10-23.
  2. Paulsen G, et al. Vitamin C and E supplementation hampers cellular adaptation to endurance training in humans: a double-blind, randomised, controlled trial. J Physiol. 2014. Read 2026-10-23.
  3. Cumming KT, et al. Effects of vitamin C and E supplementation on endogenous antioxidant systems and heat shock proteins in response to endurance training. Physiol Rep. 2014. Read 2026-10-23.
  4. Ranchordas MK, et al. Antioxidants for preventing and reducing muscle soreness after exercise. Cochrane Database Syst Rev. 2017. Read 2026-10-23.
  5. Antioxidant Supplements: What You Need To Know. National Center for Complementary and Integrative Health (US). Read 2026-10-23.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.