Vitamin C and Improved Lung Function

Research synthesisLow evidenceMixed effect size4 studies · 2 beneficial · 2 neutral · 0 harmful

Across 4 studies, 2 reported beneficial moderate-sized effects on lung function (one RCT in children of pregnant smokers, one narrative review), while 2 meta-analyses in adults with COPD and asthma found no significant effect. The only specific dose studied was 500 mg/day in the positive RCT, but the evidence is inconsistent and limited by varied populations and study designs.

Caveats: Evidence base is small (only 4 studies) — conclusions should be considered preliminary. Many of the included studies did not reach statistical significance (only 1 of 4) — effect may be smaller than the beneficial studies suggest. The only significant beneficial finding comes from a single RCT in children of pregnant smokers; meta-analyses in adults with COPD and asthma found no significant effect, raising questions about generalizability.

Generated Jul 12, 2026

Doses used in studies

mg/day: 500 (median 500, IQR 500–500) — 1 study

Safety in these studies

Overall tolerabilityReported
No adverse events at all were reported; again this is very low quality evidence.
from: Vitamin C for asthma and exercise-induced bronchoconstriction.

4 of 4 papersPopulation:

Vitamin C supplementation to pregnant smokers alters asthma- and allergy-associated CpGs in child buccal DNA at 5 years of age.
- 2025-10-03
- RCT · n = 137
- Clinical epigenetics 17(1)
- - Lyndsey E Shorey-Kendrick
  - Cindy T McEvoy
  - Kristin Milner
  - Julia Harris
  - Julie Brownsberger
  - Robert S Tepper
  - Byung Park
  - Lina Gao
  - Annette Vu
  - Cynthia D Morris
  - Emma E Thompson
  - Carole Ober
  - Eliot R Spindel
- PubMed: 41044653
- DOI: 10.1186/s13148-025-01965-2
2 Insights on
- Improved Lung Function
- High evidence
- Large Human Trial
- Clinical
We identified 9 genome-wide differentially methylated CpGs (DMCs; FDR < 0.05) and 2 differentially methylated regions (DMRs) between vitamin C and placebo subjects and one CpG associated with FEF25-75 at FDR significance. DNAm at 5 CpGs mediated a significant proportion of the vitamin C treatment effect on lung function
Effect
Beneficial
Effect size
Moderate
Significant
Yes
Dose
500 mg/day
Improvement of Lung Function by Micronutrient Supplementation in Patients with COPD: A Systematic Review and Meta-Analysis.
- 2024-04-01
- Meta-Analysis · n = 43
- Nutrients 16(7)
- - Mingxin Li
  - Liangjie Zhao
  - Chenchen Hu
  - Yue Li
  - Yang Yang
  - Xiaoqi Zhang
  - Quanguo Li
  - Aiguo Ma
  - Jing Cai
- PubMed: 38613061
- DOI: 10.3390/nu16071028
7 Insights on
- Improved Lung Function
- High evidence
- Rigorous Journal
- Clinical
vitamin C and vitamin E supplementation alone had no significant effects on lung function (p > 0.05)
Effect
Neutral
Effect size
Small
Significant
No
Vitamin C for asthma and exercise-induced bronchoconstriction.
- 2013-10-23
- Meta-Analysis · n = 419
- The Cochrane database of systematic reviews 2018(6)
- - Stephen J Milan
  - Anna Hart
  - Mark Wilkinson
- PubMed: 24154977
- DOI: 10.1002/14651858.cd010391.pub2
5 Insights on
- Improved Lung Function
- High evidence
- Clinical
In each of these outcomes there was no significant difference between vitamin C and placebo.
Effect
Neutral
Effect size
Small
Significant
No
Dose
daily vitamin C supplementation (varied doses across studies)
Vitamin C in Allergy Mechanisms and for Managing Allergic Diseases: A Narrative Review.
- 2025-05-30
- Review
- Children (Basel, Switzerland) 12(6)
- - Chiara Trincianti
  - Matteo Naso
  - Maria Angela Tosca
  - Giorgio Ciprandi
- PubMed: 40564676
- DOI: 10.3390/children12060718
5 Insights on
- Improved Lung Function
- Low evidence
Recent evidence suggests a protective role for vitamin C in asthma, with several studies reporting reduced oxidative stress markers, improved lung function, and decreased airway inflammation following regular intake or supplementation.
Effect
Beneficial
Effect size
Moderate
Dose
dietary intake (not specified)

Vitamin C and Improved Lung Function

Vitamin C supplementation to pregnant smokers alters asthma- and allergy-associated CpGs in child buccal DNA at 5 years of age.

Improvement of Lung Function by Micronutrient Supplementation in Patients with COPD: A Systematic Review and Meta-Analysis.

Vitamin C for asthma and exercise-induced bronchoconstriction.

Vitamin C in Allergy Mechanisms and for Managing Allergic Diseases: A Narrative Review.