The study and its comparison
Fifty-four young adults were randomized to combined vitamins C and E or placebo during eleven weeks of endurance training. Researchers measured running performance, oxygen uptake and muscle-biopsy markers. [1]
Both groups improved maximal oxygen uptake by about eight percent. Selected markers of mitochondrial adaptation increased with placebo but not with the vitamin combination. [1]
What the finding establishes
The cellular finding did not translate into a clear between-group difference in the tested performance outcomes. It cannot be assigned to vitamin C alone because vitamin E was also given. Funding and conflicts were not established from the abstract. The trial did not measure muscle-cramp treatment, and it does not establish that ordinary vitamin-rich foods impair training. [1]
A hypothetical distinction
Imagine a biopsy marker changes differently while fitness gains remain similar. Report the laboratory and performance outcomes separately.
| Detail | Interpretation |
|---|---|
| Measured outcome | Keep the endpoint specific |
| Study preparation | Not every retail product |
| Remaining uncertainty | Not resolved by a mechanism |
Sources for this article
- Vitamin C and E supplementation hampers cellular adaptation to endurance training in humans: a double-blind, randomised, controlled trial.
Source consulted: 2026-09-19. This is a reference resource, not a claim that we conducted the studies or tested a product.