The effects of vitamin C and E on exercise-induced physiological adaptations: a systematic review and Meta-analysis of randomized controlled trials.
Level 1 - systematic review of randomized trials
Systematic review and meta-analysis of randomized controlled trials
PubMed 31851538 · doi:10.1080/10408398.2019.1703642
What was done
Systematic review and meta-analysis of randomized controlled trials searched across Medline, Embase, and SPORTDiscus from inception to June 2019. Eligible studies enrolled adult humans consuming vitamin C and/or E alongside a supervised exercise training program lasting at least 4 weeks.
What was found
Nine trials were analyzed for aerobic adaptations and 9 for resistance training (RT) adaptations. Supplementation with vitamin C and/or E showed no statistically significant effect on: - VO2max improvements: SMD -0.14 (95% CI: -0.43 to 0.15, P = 0.35) - Endurance performance: SMD -0.01 (95% CI: -0.38 to 0.36, P = 0.97) - Lean mass post-RT: SMD -0.07 (95% CI: -0.36 to 0.23, P = 0.67) - Muscle strength post-RT: SMD -0.15 (95% CI: -0.16 to 0.46, P = 0.35) Age did not influence any of these outcomes (P > 0.05).
Why it matters
Contrary to mechanistic concerns that exogenous antioxidants suppress reactive oxygen species signaling needed for training adaptation, aggregated trial evidence indicates vitamin C and/or E supplementation does not meaningfully blunt functional or structural exercise gains.
Limits
The total number of participants and specific supplement dosing regimens were not reported in the abstract. Each sub-analysis relied on only 9 trials, and the authors noted that larger, adequately powered studies remain needed.
Cited by
- context Excessive intake of antioxidant supplements impairs normal physiological cellular signaling and adaptation.