Research synthesisLow evidenceSmall effect7 studies · 1 beneficial · 5 neutral · 1 harmful
Across 7 studies on vitamin C and mortality risk, the evidence is predominantly neutral with 5 studies reporting small null effects, 1 beneficial meta-analysis showing a moderate reduction in mortality risk (OR=0.64, 95% CI 0.51-0.80), and 1 harmful review citing harm from high-dose vitamin C in sepsis and COVID-19. The most-studied populations are clinical patients with sepsis, septic shock, or COVID-19. Median study duration was 4 days among the one study that reported duration, limiting insight into long-term effects.
- Studied populations: clinical patients with sepsis, septic shock, or COVID-19
Caveats: Many of the included studies did not reach statistical significance — effect may be smaller than the predominant direction suggests. Evidence base is small (only 7 studies) — conclusions should be considered preliminary. The only beneficial finding comes from a meta-analysis of COVID-19 patients, while the two recent large RCTs in sepsis and COVID-19 showed signs of harm with high-dose vitamin C, raising safety concerns. Most studies focused on short-term clinical settings; effects in general healthy populations are not addressed.
Generated Jul 13, 2026