Vitamin C Research
48 peer-reviewed studies · Evidence score: 8.5/10
Vitamin C reduces the severity of common colds: a meta-analysis
Hemilä H, Chalker E • BMC Public Health (2023)
Vitamin C consistently reduces the severity of the common cold across multiple trials.
- Reduces cold severity by ~8%
- Effects consistent across age groups
- Benefits from regular supplementation
Vitamin C-based regimens for sepsis and septic shock: Systematic review and meta-analysis of randomized clinical trials
Martimbianco ALC et al. • Journal of critical care (2022)
Further RCTs with higher methodological quality, an increased number of participants and assessing clinically relevant outcomes are needed to provide better decision-making guidance.
- Evidence from low to very low certainty showed that vitamin C compared to placebo may reduce all-cause mortality up to 28 days (relative risk [RR] 0.60, 95% confidence interval (CI) 0.45 to 0.80, 4 RCTs, 335 participants).
- Further RCTs with higher methodological quality, an increased number of participants and assessing clinically relevant outcomes are needed to provide better decision-making guidance.
- Further research warranted to confirm findings
The Role and Efficacy of Vitamin C in Sepsis: A Systematic Review and Meta-Analysis
Muhammad M et al. • Advances in respiratory medicine (2022)
Given its low cost and minimal adverse effects, we strongly encourage further large, randomized trials to establish vitamin C as a standard of care in sepsis management.
- For effect sizes, a confidence interval of 95% was used.
- No significant difference was found in the hospital or ICU length of stay.
- Conclusions and clinical implications: Vitamin C treatment regimens were associated with reduced mortality, SOFA score, and vasopressor requirement compared to the control in sepsis.
Efficacy of intravenous vitamin C intervention for septic patients: A systematic review and meta-analysis based on randomized controlled trials
Li T et al. • The American journal of emergency medicine (2021)
Based on current RCTs, our work indicated that mono-intravenous vitamin C therapy may reduce short-term mortality of sepsis patients, and it may protect organ functions.
- The results of meta-analysis showed that intravenous vitamin C supplementation can improve SOFA (ΔSOFA) within 72 h [RR = 1.32,95% CI(0.80,1.85), P < 0.0001] of septic patients.
- The results of Subgroup analysis showed that intravenous vitamin C alone can reduce the risk of short term mortality (28-30d) [RR = 0.61,95% CI(0.47,0.79), P = 0.0002]of sepsis patients.
- Based on current RCTs, our work indicated that mono-intravenous vitamin C therapy may reduce short-term mortality of sepsis patients, and it may protect organ functions.
Effects of Vitamin C Supplementation on Glycemic Control and Cardiovascular Risk Factors in People With Type 2 Diabetes: A GRADE-Assessed Systematic Review and Meta-analysis of Randomized Controlled Trials
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.
- 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.
- Published in Diabetes care (2021)
- Further research warranted to confirm findings
Vitamin C Supplementation for the Treatment of COVID-19: A Systematic Review and Meta-Analysis
Rawat D et al. • Nutrients (2022)
High-dose vitamin C may reduce mortality and ICU length of stay in critically ill patients.
- Potential benefits in severe infections
- High doses may reduce ICU stay
- Supports immune function during acute illness
Vitamin C supplementation for prevention and treatment of pneumonia
Padhani ZA et al. • The Cochrane database of systematic reviews (2020)
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.
- 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.
- Further research warranted to confirm findings
Vitamin C supplementation in pregnancy
Rumbold A et al. • The Cochrane database of systematic reviews (2015)
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.
- 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.
Vitamin C and COVID-19 treatment: A systematic review and meta-analysis of randomized controlled trials
Rawat D et al. • Diabetes & metabolic syndrome (2021)
No significant benefit noted with vitamin C administration in COVID-19.
- No significant benefit noted with vitamin C administration in COVID-19.
- Well-designed RCTs with standardized control group needed on this aspect.
- Further research warranted to confirm findings
Vitamin C Administration to the Critically Ill: A Systematic Review and Meta-Analysis
Langlois PL et al. • JPEN. Journal of parenteral and enteral nutrition (2019)
A moderately large treatment effect may exist, but further studies, particularly of monotherapy administration, are warranted.© 2018 American Society for Parenteral and Enteral Nutrition.
- When 9 RCTs (n = 1322) reporting mortality were pooled, vitamin C was not associated with reduced risk of mortality (risk ratio [RR] 0.72, 95% confidence interval [CI]: 0.43-1.20, P = .21).
- In multiple subgroup comparison, no statistically significant subgroup effects were observed.
- However, we did observe a tendency towards a mortality reduction (RR 0.21; 95% CI: 0.04-1.05; P = .06) when intravenous high-dose vitamin C monotherapy was administered.
Sole and combined vitamin C supplementation can prevent postoperative atrial fibrillation after cardiac surgery: A systematic review and meta-analysis of randomized controlled trials
Shi R et al. • Clinical cardiology (2018)
Use of vitamin C alone and as adjunct to other therapy can prevent POAF in patients undergoing cardiac surgery and should be recommended for patients receiving cardiac surgery for prevention of POAF.© 2018 Wiley Periodicals, Inc.
- The results remain stable and robust in subgroup and sensitivity analyses, and trial sequential analysis also confirmed that the evidence was sufficient and conclusive.
- Use of vitamin C alone and as adjunct to other therapy can prevent POAF in patients undergoing cardiac surgery and should be recommended for patients receiving cardiac surgery for prevention of POAF.© 2018 Wiley Periodicals, Inc.
- Further research warranted to confirm findings
Vitamin C for preventing and treating the common cold
Hemilä H, Chalker E • Cochrane Database of Systematic Reviews (2013)
Regular supplementation had a modest but consistent effect in reducing the duration of common cold symptoms.
- Reduces cold duration by 8% in adults
- More effective in those under physical stress
- Doesn't prevent colds in general population
Association between dietary vitamin C intake/blood level and risk of digestive system cancer: a systematic review and meta-analysis of prospective studies
Zhong J et al. • Food & function (2024)
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.
- 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.
Enhanced Vitamin C Delivery: A Systematic Literature Review Assessing the Efficacy and Safety of Alternative Supplement Forms in Healthy Adults
Calder PC et al. • Nutrients (2025)
However, further research is required to conclusively establish its effects on immune health.
- Most studies (77%) had a low risk of bias.
- In conclusion, the type and delivery modality of vitamin C can impact its bioavailability and functionality.
- Studies highlight the advantages of Calcium ascorbate EC over traditional ascorbic acid in terms of its tolerability and its potential to increase leukocyte vitamin C concentrations, crucial for immune function and protection against infection.
Microneedling as an adjuvant to topical therapies for melasma: A systematic review and meta-analysis
Bailey AJM et al. • Journal of the American Academy of Dermatology (2022)
Microneedling is useful adjuvant to topical therapies for the treatment of melasma.
- Microneedling is useful adjuvant to topical therapies for the treatment of melasma.
- Published in Journal of the American Academy of Dermatology (2022)
- Further research warranted to confirm findings
Vitamin C and E antioxidant supplementation may significantly reduce pain symptoms in endometriosis: A systematic review and meta-analysis of randomized controlled trials
Bayu P et al. • PloS one (2024)
This study suggests the potential ability of vitamin C and E in alleviating pain symptoms experienced by individuals with endometriosis.
- This study suggests the potential ability of vitamin C and E in alleviating pain symptoms experienced by individuals with endometriosis.
- Published in PloS one (2024)
- Further research warranted to confirm findings
The effects of vitamin C supplementation in the critically ill patients outcomes: A systematic review and meta-analysis of randomized controlled trials
Yong S et al. • Medicine (2024)
This study comprehensively and systematically evaluated IVVC supplementation in the critically ill through a meta-analysis of RCT.
- Compared with placebo, patients who underwent intravenous vitamin C (IVVC) have reduced duration of vasopressor used (SMD 0.26; CI 0.01-0.51; I2 = 87.0%, P = .044), mechanical ventilation (SMD -0.29; CI -0.55 to -0.03; I2 = 36.8%, P = .031).
- This study comprehensively and systematically evaluated IVVC supplementation in the critically ill through a meta-analysis of RCT.
- There is no difference except for patients who had reduced duration of vasopressor use and mechanical ventilation by the administration of IVVC.
Efficacy of vitamin C supplementation in preventing and treating complex regional pain syndrome type I (CRPS-I) in Orthopedic patients: A systematic review and meta-analysis
Ranjbar Moghaddam M et al. • International journal of orthopaedic and trauma nursing (2024)
The results of our study showed the positive effect of VC supplementation in reducing the prevalence of CRPS-I after limb surgery.
- The meta-analysis revealed that VC supplementation have effect on reducing CRPS-I post-limb surgery but this result shows that the pooled effect size is not statistically significant.
- The heterogeneity of the studies was low (I2 = 26.28%, p = 0.22).
- Further research warranted to confirm findings
The effect of vitamin C on the risk of mortality in patients with COVID-19: a systematic review and meta-analysis of randomized controlled trials
Kow CS et al. • Inflammopharmacology (2023)
Overall, evidence from RCTs suggests a survival benefit for vitamin C in patients with severe COVID-19.
- The meta-analysis of eleven trials using a random-effects model revealed significant reduction in the risk of all-cause mortality with the administration of vitamin C among patients with COVID-19 relative to no vitamin C (pooled odds ratio = 0.53; 95% confidence interval 0.30-0.92).
- Subgroup analysis of studies that included patients with severe COVID-19 also produced findings of significant mortality reduction with the administration of vitamin C relative to no vitamin C (pooled odds ratio = 0.47; 95% confidence interval 0.26-0.84).
- Overall, evidence from RCTs suggests a survival benefit for vitamin C in patients with severe COVID-19.
IV Vitamin C in Sepsis: A Latest Systematic Review and Meta-Analysis
Wen C et al. • International journal of clinical practice (2023)
More high-quality, multicenter RCTs are needed to provide more substantial evidence on the efficacy and safety of IV vitamin C for sepsis.Copyright © 2023 Chengli Wen et al.
- Our review demonstrates that intravenous (IV) vitamin C might improve short-term mortality (RR, 0.82; 95% CI, 0.65-1.02; P=0.07; and I 2 = 45%) and overall mortality (RR, 0.86; 95% CI, 0.74-1.01; P=0.06; and I 2 = 51%) of patients with sepsis.
- Moreover, the SOFA score of patients with sepsis improved significantly after treatment with vitamin C for over 72 hours (RR, 0.26; 95% CI, 0.09-0.42; P=0.002; and I 2 = 0%).
- The main results of our study were moderate-quality evidence.