Vitamin C for Immune Support
Water-soluble antioxidant vitamin and essential cofactor for collagen synthesis and non-haem iron absorption; supports immune cell function and skin integrity, and cannot be made by the human body.
Vitamin C for Immune Support
1 of 3 results reported a benefit, from 1 published study.
1 review of trials · the chart counts everything measured
- 1 reported a benefit
- 2 no clear benefit
Colour keyReported a benefitNo clear benefitUnclearPossible harmAmber is for highlights, such as where the most research is. It never means a result was good.
- Respiratory infection casesNo clear difference6% lower risk1 review of trials2022 study ↗
- Respiratory infection durationSlight effectslightly better than the comparison group1 review of trials2022 study ↗
- Respiratory infection severityNo clear differencenegligible standardised effect1 review of trials2022 study ↗
These are the figures the studies reported, not a prediction for any one person. Where several studies measured the same thing in the same unit, we show a simple average and say so. Every result is listed below.
See every resultThe connection
Frequent illness, weak immune response, slow recovery from infections.
Also known as: Ascorbic Acid
Vitamin C × Immune Support: at a glance
Every published result for this pair, extracted and audited.
These charts count reported findings from published studies, grouped by reported benefit and study design. Study design is not a certainty grade.
Vitamin C / Immune Support: reported findings; one study may contribute several findings.
What the evidence shows
What this means: Counts describe research quantity, not treatment effectiveness or certainty.
| Category | Findings (count) |
|---|---|
| Benefit | 1 |
| No benefit | 2 |
Study designs behind these findings
What this means: Counts describe research quantity, not treatment effectiveness or certainty.
| Category | Findings (count) |
|---|---|
| Meta-analysis | 3 |
- Studies
- 1
| Study | Outcome | Reported result | Uncertainty (as reported) | Study duration |
|---|---|---|---|---|
| Effect of Vitamin C Supplements on Respiratory Tract Infections: A Systematic Review and Meta-Analysis. (PMID 34967304) | duration of respiratory infection | -0.36 | 95% CI -0.62 to -0.09, P = 0.01 | Not reported |
| Effect of Vitamin C Supplements on Respiratory Tract Infections: A Systematic Review and Meta-Analysis. (PMID 34967304) | incidence of respiratory illness | 0.94 | 95% confidence interval of 0.87 to 1.01, P= 0.09 | Not reported |
| Effect of Vitamin C Supplements on Respiratory Tract Infections: A Systematic Review and Meta-Analysis. (PMID 34967304) | severity of respiratory illness | 0.14 | 95% CI -0.02 to 0.30: I2 = 22%, P=0.09 | Not reported |
Study results, as reported by the publications
Every measured outcome, one row per finding - numbers exactly as reported. Units are preserved where supplied; missing units are not inferred.
| Study and type | Reported sample and duration | Outcome measured | Reported result | What studies found |
|---|---|---|---|---|
| PMID 34967304 2022 Meta-analysis | Sample (as reported): Not reportedDuration: Not reported | duration of respiratory infection | -0.36 (95% CI -0.62 to -0.09, P = 0.01) | Benefit |
| PMID 34967304 2022 Meta-analysis | Sample (as reported): Not reportedDuration: Not reported | incidence of respiratory illness | 0.94 (95% confidence interval of 0.87 to 1.01, P= 0.09) | No benefit |
| PMID 34967304 2022 Meta-analysis | Sample (as reported): Not reportedDuration: Not reported | severity of respiratory illness | 0.14 (95% CI -0.02 to 0.30: I2 = 22%, P=0.09) | No benefit |
Vitamin C × Immune Support: the evidence base
Hand-selected PubMed studies, linked to the originals.
Ordered by strength of evidence, then result direction.
01Comparison of adjuvant and neoadjuvant therapies for muscle invasive bladder cancer: A network meta-analysisPetrelli F, et al. · Urologic oncology · 2026PMID 40935764 ↗02Surviving Sepsis Campaign International Guidelines for the Management of Sepsis and Septic Shock in Children 2026Weiss SL, et al. · Pediatric critical care medicine : a journal of the Society of Critical Care Medicine and the World Federation of Pediatric Intensive and Critical Care Societies · 2026PMID 41869844 ↗03Surviving Sepsis Campaign International Guidelines for the Management of Sepsis and Septic Shock in Children 2026Weiss SL, et al. · Intensive care medicine · 2026PMID 41870559 ↗04Effect of nutritional interventions on the psychological symptoms of premenstrual syndrome in women of reproductive age: a systematic review of randomized controlled trialsRobinson J, et al. · Nutrition reviews · 2025PMID 38684926 ↗05Granulomatous Reactions From Microneedling: A Systematic Review of the LiteratureFriedmann DP, et al. · Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.] · 2025PMID 39584690 ↗06Vitamin D's Impact on Cancer Incidence and Mortality: A Systematic ReviewWimalawansa SJ · Nutrients · 2025PMID 40732958 ↗Community experiences
Contributors volunteered; this does not establish treatment effectiveness or population incidence.
Reported changes
No publishable community breakdown is available. This does not establish that no reports exist.