Vitamin C

Vitamin C is required for collagen formation, so tissue repair is a biologically sensible area to study. A systematic review of tissue healing found possible benefits in selected conditions, especially pressure ulcers, but the studies and clinical situations were not uniform.

A review focused on musculoskeletal injuries found promising preclinical findings but few human studies and concluded that more clinical research was needed before implementing vitamin C as a routine post-injury supplement. A nutrient’s role in a pathway is not the same as proof that an extra capsule speeds recovery after every injury.[4][6]

Antioxidant marketing often frames exercise-related oxidative stress as something that should be neutralized. In a meta-analysis of randomized trials, vitamin C and vitamin E did not meaningfully change improvements in aerobic capacity, endurance performance, lean mass, or strength during training.

That finding does not say vitamin C is bad for athletes or that food sources are unhelpful. It says a supplement should not be sold as a guaranteed performance or adaptation enhancer simply because it participates in antioxidant chemistry.[5][1]

Fruits and vegetables provide vitamin C along with fiber and other nutrients. Supplements are usually ascorbic acid, but also appear as mineral ascorbates or blends with bioflavonoids; consumer guidance from the NIH says research has not shown one form to be better than the others.

Too much vitamin C can cause diarrhea, nausea, and stomach cramps. The adult upper limit is 2,000 mg per day from all sources. High-dose use deserves extra caution with iron-overload disorders, kidney concerns, and cancer treatment because supplements can interact with medical care.[1][2]