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Vc8.0
Vitamin C Research
Likely helps
1,026 peer-reviewed studies
What the evidence says
Likely helps
Vitamin C appears to help in 12 of 17 studies with measurable effects — the evidence leans clearly favourable.
Most evidence is from high-quality meta-analyses and randomised trials published 1997–2026 with a typical study size of 69 participants.
Based on 1,026 studies · 164 meta-analyses · 802 RCTs · 48,478 total participants
Confidence
High confidence
What the studies found
12helped4unclear1didn't help· 1009 more without graded effect data
By outcome
Therapeutic & clinical
Mostly mechanism / observational127 studies
InflammationModest reduction in inflammatory markers · 2-4 weeks
Mostly mechanism / observational78 studies
Heart & blood pressure
Mostly mechanism / observational71 studies
Women's healthProvides essential nutrients for healthy pregnancy · Ongoing
Mostly mechanism / observational60 studies
Kidney & renal health
Mostly mechanism / observational50 studies
Immune supportMay reduce cold duration by 8% in adults · Ongoing supplementation
Probably helps48 studies
Anemia & hematology
Mostly mechanism / observational44 studies
RecoveryReduces oxidative stress from intense exercise · 1-2 weeks
Probably helps39 studies
Glucose & metabolic
Mostly mechanism / observational30 studies
Skin healthSupported collagen synthesis and skin protection within 4-8 weeks · 4-8 weeks
While evidence from short-term studies suggests that vitamin C supplementation may improve glycemic control and BP in people with type 2 diabetes, vitamin C supplementation cannot currently be recommended as a therapy until larger, long-term, and high-quality trials confirm these findings.
Mason SA et al. · Diabetes care (2021)
While evidence from short-term studies suggests that vitamin C supplementation may improve glycemic control and BP in people with type 2 diabetes, vitamin C supplementation cannot currently be recommended as a therapy until larger, long-term, and high-quality trials confirm these findings.
3In-hospital mortalityMeta-AnalysisCited 29×n=1,800 · large study2022
The use of vitamin C reduces hospital mortality. The length of stay in the ICU is longer among patients treated with vitamin C.
Olczak-Pruc M et al. · Nutrients (2022)
Large benefit
← WorseNo effectBetter →
Likely real
In-hospital mortality with and without vitamin C supplementation was 24.1% vs. 33.9% (OR = 0.59; 95%CI: 0.37 to 0.95; p = 0.03), respectively.
The ICU length of stay was longer in patients treated with vitamin C vs. standard therapy, 11.1 (7.3) vs. 8.3 (4.7) days (MD = 1.91; 95%CI: 0.89 to 2.93; p < 0.001), respectively.
Despite some evidence of the usefulness of vitamin C in modifying the course of COVID-19, it is too early to modify guidelines and recommendations.
4Mortality due to pneumoniaMeta-AnalysisCited 30×n=2,774 · very large study2020
Due to the small number of included studies and very low quality of the existing evidence, we are uncertain of the effect of vitamin C supplementation for the prevention and treatment of pneumonia.
Padhani ZA et al. · The Cochrane database of systematic reviews (2020)
No clear effect
← WorseNo effectBetter →
We are uncertain of the effect of vitamin C supplementation on mortality due to pneumonia (RR 0.21, 95% CI 0.03 to 1.66; 1 study, 57 participants; very low-quality evidence).
Further good-quality studies are required to assess the role of vitamin C supplementation in the prevention and treatment of pneumonia.
5Term PROM with vitamin C and E supplementationMeta-AnalysisCited 109×n=20,038 · very large study2015
The data do not support routine vitamin C supplementation alone or in combination with other supplements for the prevention of fetal or neonatal death, poor fetal growth, preterm birth or pre-eclampsia.
Rumbold A et al. · The Cochrane database of systematic reviews (2015)
Huge harm
← WorseNo effectBetter →
Conversely, the risk of term PROM was increased when supplementation included vitamin C and vitamin E (average RR 1.73, 95% CI 1.34 to 2.23; 3060 participants; two studies; I² = 0%).
The data do not support routine vitamin C supplementation alone or in combination with other supplements for the prevention of fetal or neonatal death, poor fetal growth, preterm birth or pre-eclampsia.
Further research is required to elucidate the possible role of vitamin C in the prevention of placental abruption and prelabour rupture of membranes.
8Digestive system cancer riskMeta-AnalysisCited 9×n=498 · medium study2024
Plasma vitamin C has a significant reduction effect on the incidence of gastric cancer only, but additional large-scale clinical studies are needed to determine its impact on the incidence of DSCs.
Zhong J et al. · Food & function (2024)
Noticeable benefit
← WorseNo effectBetter →
Vitamin C intake significantly reduced DSCs risk (RR = 0.88, 95% confidence interval (CI) 0.83 to 0.93).
These estimates suggest that vitamin C intake could significantly reduce gastrointestinal cancer incidence, including OPE, gastric, and colon cancers.
Plasma vitamin C has a significant reduction effect on the incidence of gastric cancer only, but additional large-scale clinical studies are needed to determine its impact on the incidence of DSCs.