The effects of vitamin C and E on exercise-induced physiological adaptations: a systematic review and Meta-analysis of randomized controlled trials

Tom Cliffordab* , Owen Jeffriesa , Emma J. Stevensona & Kelly A. Bowden Daviesaa Institute of Cellular Medicine, Newcastle University, Newcastle on Tyne, UK; b School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough, UKThe material presented in this manuscript is original and it has not been submitted for publication elsewhere while under consideration by Critical Reviews in Food Science and Nutrition.Supplemental data for this article is available online at https://doi.org/10.1080/10408398.2019.1703642.CONTACT Tom Clifford t.clifford@lboro.ac.uk School of Sport, Exercise and Health Sciences, Loughborough University, Loughborough LE11 3TU, UK.AbstractWe conducted a systematic review and meta-analysis of randomized controlled trials examining the effect of vitamin C and/or E on exercise-induced training adaptations. Medline, Embase and SPORTDiscus databases were searched for articles from inception until June 2019. Inclusion criteria was studies in adult humans where vitamin C and/or E had to be consumed alongside a supervised exercise training program of ≥4 weeks. Nine trials were included in the analysis of aerobic exercise adaptations and nine for resistance training (RT) adaptations. Vitamin C and/or E did not attenuate aerobic exercise induced improvements in maximal aerobic capacity (V̇O2max) (SMD −0.14, 95% CI: −0.43 to 0.15, P = 0.35) or endurance performance (SMD −0.01, 95% CI: −0.38 to 0.36, P = 0.97). There were also no effects of these supplements on lean mass and muscle strength following RT (SMD −0.07, 95% CI: −0.36 to 0.23, P = 0.67) and (SMD −0.15, 95% CI: −0.16 to 0.46, P = 0.35), respectively. There was also no influence of age on any of these outcomes (P > 0.05). These findings suggest that vitamin C and/or E does not inhibit exercise-induced changes in physiological function. Studies with larger sample sizes and adequate power are still required.