Long-term use of supplemental multivitamins, vitamin C, vitamin E, and folate does not reduce the risk of lung cancer.

American journal of respiratory and critical care medicine
Q1
Mar 2008
Citations:114
Influential Citations:3
Observational Studies (Human)
83
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Enhanced Details

Methods
Design: prospective cohort (VITAL). Participants: 77,126 men and women aged 50-76 years from Washington State; baseline 24-page questionnaire; outcome: incident lung cancer identified via Seattle-Puget Sound SEER registry; follow-up through December 31, 2005 (mean 4.05 years); 521 cases; Analysis used Cox regression with age as the time variable; left truncation; robust standard errors; adjustments for smoking (years smoked, pack-years, pack-years squared) and sex; Exclusions: prior lung cancer at baseline; exposure measured as 10-year average supplement use.
Intervention
10-year average daily intake of oral supplements: multivitamins (pills/week), vitamin C (mg/day), vitamin E (mg/day), and folate (mg/day); duration prior to baseline: 10 years.
Results
Long-term use of supplemental multivitamins, vitamin C, and folate was not associated with a decreased risk of lung cancer. Supplemental vitamin E showed a small, dose-dependent increase in risk, strongest among current smokers and for NSCLC; HR 1.05 per 100 mg/day (95% CI 1.00–1.09; P=0.03); after adjusting for dietary vitamin E, HR 1.04 (95% CI 1.00–1.09; P=0.08). For NSCLC, HR 1.07 per 100 mg/day (95% CI 1.02–1.12; P=0.01). At 400 mg/day for 10 years, risk ≈28% higher. Current smokers in the highest vitamin E dose category had HR 1.59 (95% CI 1.05–2.41). No significant associations for vitamin C or folate with overall risk; authors conclude that these supplements are unlikely to reduce lung cancer risk, and supplemental vitamin E may increase risk; counsel patients against using these supplements to prevent lung cancer.
Limitations
Observational design with potential residual confounding; self-reported supplement use may lead to exposure misclassification; predominantly white cohort with fewer current smokers, limiting generalizability; limited power to detect small risk differences (≥30%); nonrandomized.

Abstract

RATIONALE Lung cancer is the leading cause of cancer-related mortality in the United States. Although supplements are used by half the population, limited information is available about their specific effect on lung cancer risk. OBJECTIVES To explo...