Efficacy of Vitamin C Supplementation on Collagen Synthesis and Oxidative Stress After Musculoskeletal Injuries: A Systematic Review

BACKGROUND: Recent investigations on the biochemical pathways after a musculoskeletal injury have suggested that vitamin C (ascorbic acid) may be a viable supplement to enhance collagen synthesis and soft tissue healing. PURPOSE: To (1) summarize vitamin C treatment protocols; (2) report on the efficacy of vitamin C in accelerating healing after bone, tendon, and ligament injuries in vivo and in vitro; and (3) report on the efficacy of vitamin C as an antioxidant protecting against fibrosis and promoting collagen synthesis. STUDY DESIGN: Systematic review; Level of evidence, 2. METHODS: A systematic review was performed, with the inclusion criteria of animal and human studies on vitamin C supplementation after a musculoskeletal injury specific to collagen cross-linking, collagen synthesis, and biologic healing of the bone, ligament, and tendon. RESULTS: The initial search yielded 286 articles. After applying the inclusion and exclusion criteria, 10 articles were included in the final analysis. Of the preclinical studies evaluating fracture healing, 2 studies reported significantly accelerated bone healing in the vitamin C supplementation group compared with control groups. The 2 preclinical studies evaluating tendon healing reported significant increases in type I collagen fibers and scar tissue formation with vitamin C compared with control groups. The 1 preclinical study after anterior cruciate ligament (ACL) reconstruction reported significant short-term (1-6 weeks) improvements in ACL graft incorporation in the vitamin C group compared with control groups; however, there was no long-term (42 weeks) difference. Of the clinical studies evaluating fracture healing, 1 study reported no significant differences in the rate of fracture healing at 50 days or functional outcomes at 1 year. Vitamin C supplementation was shown to decrease oxidative stress parameters by neutralizing reactive oxygen species through redox modulation in animal models. No animal or human studies reported any adverse effects of vitamin C supplementation. CONCLUSION: Preclinical studies demonstrated that vitamin C has the potential to accelerate bone healing after a fracture, increase type I collagen synthesis, and reduce oxidative stress parameters. No adverse effects were reported with vitamin C supplementation in either animal models or human participants; thus, oral vitamin C appears to be a safe supplement but lacks clinical evidence compared with controls. Because of the limited number of human studies, further clinical investigations are needed before the implementation of vitamin C as a postinjury supplement.