title: Vitamin C supplements and the risk of age-related cataract: a population-based prospective cohort study in women.
abstract: BACKGROUND
  Experimental animal studies have shown adverse effects of high-dose vitamin C supplements on age-related cataract.
  
  
  OBJECTIVE
  We examined whether vitamin C supplements (approximately 1000 mg) and multivitamins containing vitamin C (approximately 60 mg) are associated with the incidence of age-related cataract extraction in a population-based, prospective cohort of women.
  
  
  METHODS
  Our study included 24,593 women aged 49-83 y from the Swedish Mammography Cohort (follow-up from September 1997 to October 2005). We collected information on dietary supplement use and lifestyle factors with the use of a self-administrated questionnaire. Cataract extraction cases were identified by linkage to the cataract extraction registers in the geographical study area.
  
  
  RESULTS
  During the 8.2 y of follow-up (184,698 person-years), we identified 2497 cataract extraction cases. The multivariable hazard ratio (HR) for vitamin C supplement users compared with that for nonusers was 1.25 (95% CI: 1.05, 1.50). The HR for the duration of >10 y of use before baseline was 1.46 (95% CI: 0.93, 2.31). The HR for the use of multivitamins containing vitamin C was 1.09 (95% CI: 0.94, 1.25). Among women aged > or = 65 y, vitamin C supplement use increased the risk of cataract by 38% (95% CI: 12%, 69%). Vitamin C use among hormone replacement therapy users compared with that among nonusers of supplements or of hormone replacement therapy was associated with a 56% increased risk of cataract (95% CI: 20%, 102%). Vitamin C use among corticosteroid users compared with that among nonusers of supplements and corticosteroids was associated with an HR of 1.97 (95% CI: 1.35, 2.88).
  
  
  CONCLUSIONS
  Our results indicate that the use of vitamin C supplements may be associated with higher risk of age-related cataract among women.
authors.affiliation: Divisions of Nutritional Epidemiology, Karolinska Institutet, Stockholm, Sweden.
authors.forename: Susanne
authors.initials: S
authors.lastname: Rautiainen
authors.forename: Birgitta Ejdervik
authors.initials: BE
authors.lastname: Lindblad
authors.forename: Ralf
authors.initials: R
authors.lastname: Morgenstern
authors.forename: Alicja
authors.initials: A
authors.lastname: Wolk
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001205:Ascorbic Acid / Q000008:administration & dosage* / Q000009:adverse effects; D002386:Cataract / Q000139:chemically induced / Q000453:epidemiology*; D015331:Cohort Studies; D019587:Dietary Supplements / Q000009:adverse effects; D005260:Female; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires; D013548:Sweden / Q000453:epidemiology
chemical_list: D001205:Ascorbic Acid