title: Beta-carotene in multivitamins and the possible risk of lung cancer among smokers versus former smokers: a meta-analysis and evaluation of national brands.
abstract: BACKGROUND
  Some studies have suggested that beta-carotene supplementation may increase the risk of lung cancer, particularly among smokers or former smokers. Beta-carotene, a provitamin A, is available in multivitamins. In the current study, the authors investigated the risk of lung cancer associated with beta-carotene in smokers or former smokers and surveyed the beta-carotene content in national brand multivitamins.
  
  
  METHODS
  The authors systemically reviewed the published literature using a search of the MEDLINE database and performed a meta-analysis of large randomized trials that reported on the effect of beta-carotene supplementation on the incidence of lung cancer among smokers or former smokers. A sample of multivitamins was evaluated for their beta-carotene content and the suggested daily dosage.
  
  
  RESULTS
  Four studies contributing 109,394 subjects were available for analysis. The average daily beta-carotene dosage in these trials ranged from 20 to 30 mg daily. Among current smokers, beta-carotene supplementation was found to be significantly associated with an increased risk of lung cancer (odds ratio [OR], 1.24; 95% confidence interval [95% CI], 1.10-1.39). Among former smokers, there was no significant increase noted (OR, 1.10; 95% CI, 0.84-1.45). In a sample of 47 common multivitamins, beta-carotene was present in 70% of the identified formulas. The median dosage of beta-carotene was 0.3 mg (range, 0-17.2 mg) daily. The beta-carotene content was found to be significantly higher among multivitamins sold to improve visual health than among other multivitamins, with a median daily dosage of 3 mg (range, 0-24 mg).
  
  
  CONCLUSIONS
  High-dose beta-carotene supplementation appears to increase the risk of lung cancer among current smokers. Although beta-carotene was prevalent in multivitamins, high-dose beta-carotene was observed among multivitamin formulas sold to promote visual health.
authors.affiliation: Thoracic Oncology Program, H. Lee Moffitt Cancer Center and Research Institute, University of South Florida, 12902 Magnolia Drive, Tampa FL 33612, USA. tanvett@moffitt.org
authors.forename: Tawee
authors.initials: T
authors.lastname: Tanvetyanon
authors.forename: Gerold
authors.initials: G
authors.lastname: Bepler
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D019587:Dietary Supplements / Q000009:adverse effects*; D005260:Female; D006801:Humans; D008175:Lung Neoplasms / Q000453:epidemiology*; D008297:Male; D008875:Middle Aged; D016032:Randomized Controlled Trials as Topic; D018570:Risk Assessment; D012907:Smoking / Q000009:adverse effects*; D016540:Smoking Cessation; D019207:beta Carotene / Q000008:administration & dosage / Q000009:adverse effects* / Q000032:analysis
chemical_list: D019207:beta Carotene