Association between vitamin C intake and lung cancer: a dose-response meta-analysis.
Level 3 - non-randomized controlled study
Meta-analysis of observational epidemiological studies
PubMed 25145261 · doi:10.1038/srep06161
What was done
A dose-response meta-analysis of epidemiological studies searched through December 2013 in PubMed, Web of Knowledge, and Wan Fang Med Online to evaluate the association between vitamin C intake and lung cancer risk. Pooled estimates were calculated using a random-effects model. Publication bias was evaluated with Begg's funnel plot and Egger's regression asymmetry test. Eighteen articles reporting 21 studies involving 8,938 lung cancer cases were included.
What was found
Highest versus lowest vitamin C intake was significantly associated with reduced lung cancer risk (summary RR = 0.829, 95% CI = 0.734-0.937, I² = 57.8%), particularly in the United States and prospective studies. A linear dose-response relationship showed risk decreased by 7% per 100 mg/day increase in vitamin C intake (summary RR = 0.93, 95% CI = 0.88-0.98). No publication bias was detected.
Why it matters
It aggregates epidemiological data to quantify a dose-response link between higher vitamin C intake and lower lung cancer incidence, estimating a 7% risk reduction per 100 mg/day intake.
Limits
The analysis synthesizes observational studies, which cannot establish causality and remain susceptible to residual confounding. Moderate heterogeneity was present across studies (I² = 57.8%), and total non-case participant numbers were not stated in the abstract.
Cited by
- supports A meta-analysis of 14 studies comprising over 6,000 lung cancer cases found that for every 100-milligram daily increase in vitamin C intake among men, the risk of lung cancer decreased by 7%.