Vitamin C supplementation for asthma.
Level 1 - systematic review of randomized trials
Systematic review of randomized controlled trials
PubMed 19160185 · doi:10.1002/14651858.CD000993.pub3
What was done
A Cochrane systematic review assessed randomized controlled trials evaluating vitamin C supplementation for asthma treatment (updated searches to August 2008). Two independent reviewers screened search results from the Cochrane Airways Review Group register and reference lists, extracting data on lung function, symptom scores, IgE levels, and inhaled steroid use using standard forms.
What was found
Nine randomized controlled trials were included, enrolling a total of 330 participants. Reporting was generally poor, with only five trials providing extractable numerical data. One small study reported a significant difference in percent drop in FEV1 post-exercise; no other specific numerical results were reported in the abstract.
Why it matters
Current evidence from randomized trials is insufficient to recommend vitamin C supplementation for the treatment of asthma.
Limits
The overall sample size was small (330 total participants across 9 trials), study designs varied substantially, reporting across trials was poor, and four trials provided no numerical data.
Cited by
- context In a study of 41 asthma patients, daily supplementation with 1 gram of vitamin C for 14 weeks resulted in fewer and less severe asthma attacks compared to placebo.