Taking vitamin C supplements prevents respiratory virus infections. Taking zinc supplements does not prevent respiratory virus infections.
See the scientific wording
Vitamin C supplementation prevents respiratory virus infections, while zinc supplementation does not prevent respiratory virus infections.
There's disagreement
The 5 studies we reviewed point in different directions — there's no clear consensus.
What the research says
5 studies reviewedSupporting (2)
Systematic Review With Meta-AnalysisMeta-analysis2021
The study showed that taking vitamin C slightly lowers the chance of getting a respiratory infection, and taking zinc does not lower the chance of getting one, which matches what the claim says.
Narrative ReviewReview2017
This study shows that vitamin C can help prevent and shorten colds, but it doesn't say anything about zinc, so it only partly supports the claim.
Contradicting (3)
Vitamin C for preventing and treating the common cold.
Systematic Review With Meta-AnalysisMeta-analysis2013
The study shows that taking vitamin C every day doesn't stop most people from catching colds, but it helps people who do intense exercise. It doesn't say anything about zinc.
Vitamin C reduces the severity of common colds: a meta-analysis
Systematic Review With Meta-AnalysisMeta-analysis2023
Taking vitamin C doesn't stop you from catching a cold, but it might make your cold less severe. The study didn't look at zinc, so it can't say whether zinc helps or not.
Impact of zinc on immunometabolism and its putative role on respiratory diseases
Narrative ReviewReview2025
This study shows that taking zinc can help prevent some respiratory infections like pneumonia, which goes against the claim that zinc doesn't help.
Quality-weighted scoring: we follow the GRADE framework — each study is rated High, Moderate, Low, or Very Low based on study design, methodology rigor, and risk of bias. A single high-quality RCT can outweigh several weaker observational studies.
Scores reflect study quality, not just count.
Score breakdown, mechanism chain, raw evidence, ideal studies needed & 2 supporting, 3 contradicting studies
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