The Claim

Vitamin D supplementation at daily doses of 400–1000 IU may reduce the risk of acute respiratory infections, with an odds ratio of 0.70 (95% CI 0.55–0.89) based on 10 trials involving 2,305 participants, though higher doses showed no significant benefit and this finding was not robustly supported by multivariable analysis.

Source: Vitamin D supplementation to prevent acute respiratory infections: systematic review and meta-analysis of stratified aggregate data

What the research says

Challenges is higher

Challenge is ahead, but a single strong supporting study can change this.

Supports
0score
Challenges
45score

These are independent scores, not a percentage. Higher-grade studies count more, so a single strong opposing study can outweigh several weaker ones.

Cause and effect
1 study reviewed
In plain English

Taking a small daily dose of vitamin D might help lower your chances of getting colds or other breathing infections, but taking more doesn't seem to help extra, and scientists aren't totally sure about this yet.

See the scientific wording

Vitamin D supplementation at daily doses of 400–1000 IU may reduce the risk of acute respiratory infections, with an odds ratio of 0.70 (95% CI 0.55–0.89) from 10 trials involving 2,305 participants, but higher doses showed no significant benefit and this finding was not robustly supported by multivariable analysis.

What the research says

1 study
  1. Study: Vitamin D supplementation to prevent acute respiratory infections: systematic review and meta-analysis of stratified aggregate data

    The study looked at vitamin D for colds and found it didn't really help overall, which goes against the claim that small daily doses reduce infection risk.

Score breakdown, mechanism chain, raw evidence, ideal studies needed & 1 supporting studies

Fit Body Science verdict — we translate health claims into clear verdicts backed by peer-reviewed research.

Not medical advice. For informational purposes only. Always consult a qualified healthcare professional before making health decisions.