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

Systematic review and meta-analysis of randomized controlled trials in adults undergoing supervised aerobic or resistance training. Participants were generally healthy, non-elite, and often sedentary or recreationally active, with some older adults and one study in patients with claudication pain from peripheral arterial disease.

Oral vitamin C and/or vitamin E supplementation was given alongside supervised exercise training, most commonly vitamin C 1000 mg/day and vitamin E 400 IU/day. Regimens included vitamin C alone, vitamin E alone, or both vitamins together, with supplementation lasting 4 to 24 weeks; in two trials, supplements were started 4 weeks before training.

Vitamin C and/or vitamin E did not meaningfully blunt training adaptations. Pooled effects were null for VO2max (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 (SMD -0.07, 95% CI -0.36 to 0.23, P = 0.67), and muscle strength (SMD -0.15, 95% CI -0.16 to 0.46, P = 0.35). Age did not modify the results, and adverse events were not reported.

The evidence base was small, with modest numbers of participants across outcomes and variable supplement regimens and training protocols. The included studies were heterogeneous in population, exercise type, and duration, and adverse event reporting was absent, limiting safety interpretation. Larger, well-powered randomized trials are needed.