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Vitamin C
Supplements · Emerging evidence
Evidence
35
Impact
18
Vitamin C does not prevent the common cold in the general population, though it may modestly shorten its duration.
- Studies
- 9
- RCTs
- 0
- Meta-analyses
- 9
Research summary
- A well-known Cochrane review found that regular vitamin C supplementation does not reduce the incidence of the common cold in the general population, though it modestly shortens cold duration and severity — a nuance later confirmed by dedicated meta-analyses of supplementary and higher-dose regimens.
- For cardiovascular outcomes, prospective-study meta-analyses link higher vitamin C intake and circulating levels to lower stroke risk, and a GRADE-assessed meta-analysis found modest improvements in glycemic control and cardiovascular risk factors in people with type 2 diabetes, though a specific trial-level meta-analysis on preventing atrial fibrillation in high-risk patients found supportive but limited evidence.
- Broader dose-response meta-analyses of dietary antioxidants (including vitamin C) show associations with lower all-cause mortality, but these are observational and cannot isolate vitamin C's individual contribution.
- Overall, vitamin C's most commonly assumed benefit — cold prevention — is not supported by the evidence, while its more modest, specific benefits are real but limited.
Immune Function
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