Vitamin C shows little sign of speeding recovery after exercise

Hard exercise generates oxidative stress and inflammation, and the theory goes that this can slow recovery and blunt performance. Vitamin C is a potent antioxidant, which has made it a perennial candidate for softening exercise-induced muscle damage and calming inflammatory and oxidative biomarkers afterwards. Plenty of athletes and gym-goers already take it for exactly this reason. Whether the trial evidence actually backs the habit is the question this review set out to answer.

The researchers conducted a systematic review and meta-analysis following PRISMA guidelines, registered in advance on PROSPERO. Twelve randomised controlled trials met their criteria, all in adults exposed to a range of exercise protocols, comparing vitamin C in various forms against placebo. The primary outcomes were the inflammatory markers CRP and IL-6 and the oxidative stress marker MDA. They assessed risk of bias with a standard tool and graded the certainty of the evidence.

Pooled analyses showed no significant effect of vitamin C on IL-6, from 2 trials covering 31 people, or on MDA, from 3 trials covering 41 people. CRP was the exception: a significant reduction across 2 trials covering 52 people. The MDA results disagreed substantially between studies, while the IL-6 and CRP analyses were consistent. Risk of bias was mostly rated as some concerns or high, and the certainty of evidence was judged low for IL-6 and CRP and very low for MDA.

This sits awkwardly with the popular framing of antioxidants as recovery tools: two of the three markers did not budge, and the one that did moved on low-certainty evidence from two small trials. The authors explicitly describe the findings as hypothesis-generating rather than conclusive, pointing to the small trial sizes, methodological limitations and imprecision throughout. Larger, well-controlled trials are needed before anyone can say whether the CRP signal is real. The question of whether biomarker changes translate into feeling or performing better is left open entirely.

If vitamin C is in your supplement stack specifically for recovery, this evidence gives you little to lean on: most of the markers it is supposed to improve stayed put. The single positive finding, a drop in CRP, is too thinly supported to carry the claim on its own. Nothing here speaks to vitamin C's other roles in general health. It simply suggests the post-workout recovery pitch is, for now, running ahead of the data.