The Effects of Strength Training Combined with Vitamin C and E Supplementation on Skeletal Muscle Mass and Strength: A Systematic Review and Meta-Analysis

This was a systematic review and meta-analysis of resistance-training studies in adults and older adults, including healthy and nonhealthy participants, trained and sedentary individuals, and both men and women. The review compared strength training with vitamin C and E supplementation versus training without supplementation or placebo.

Chronic vitamin C and vitamin E supplementation was given alongside resistance training across the included trials, most commonly vitamin C 1000 mg/day combined with vitamin E 235 mg/day, 400 IU/day, or 600 mg/day depending on the study. Regimens were administered during the training period and compared with resistance training alone or placebo.

Overall, chronic vitamin C and E supplementation did not improve muscle strength or hypertrophy during resistance training. In the meta-analysis of isokinetic strength from 3 studies, the pooled effect was not significant (MD = 5.09 N/m; 95% CI: -1.39 to 11.41; P = 0.13; experimental n = 37; control n = 34). Individual trials were mostly null for hypertrophy, although some reported smaller muscle size gains with antioxidants, such as greater rectus femoris thickness increase in placebo than in antioxidants (+3.4 mm vs +1.9 mm) and no meaningful differences in several strength outcomes. The authors concluded that these antioxidants do not provide an ergogenic benefit for strength gains and may blunt hypertrophy in some settings.

The evidence base was small and heterogeneous, with only 3 studies contributing to the pooled strength analysis. Trials varied in population, training status, dose, duration, and exercise protocol, which limits comparability and generalizability. Reporting of adverse events was absent in the provided text, and several outcomes were not consistently available across studies.