title: Prospective study showing that dietary vitamin C reduced the risk of age-related cataracts in a middle-aged Japanese population.
abstract: BACKGROUND
  In Western countries, many epidemiological studies have demonstrated that specific dietary nutrients are associated with the risk of developing age-related cataracts. These reports have suggested that dietary antioxidant vitamins, in particular vitamin C, can play a role in preventing the onset or progression of age-related visual impairment. However, few prospective studies have examined this relationship in a general Asian population. Therefore, in this study, we investigated whether dietary vitamin C was associated with a lower incidence of age-related cataracts by performing a 5-year prospective population-based analysis using data from a cohort of over 30,000 Japanese residents recruited to the Japan Public Health Center-based Prospective Study (JPHC Study) cohort I.
  
  
  OBJECTIVE
  We carried out a prospective analysis of the association between vitamin C intake and age-related cataracts among middle-aged Japanese, to study the effects of dietary antioxidants in an Asian population.
  
  
  METHODS
  This 5-year population-based study included 16,415 men and 18,771 women (aged 45-64 years), who were recruited onto the JPHC Study and had not reported cataracts in baseline surveys. Vitamin C was calculated from the nutrient intake assessed by self-administered food-frequency questionnaires (FFQ). Self-reported questionnaires were used to assess two endpoints: diagnosis or extraction of cataracts.
  
  
  RESULTS
  At follow-up, 216 men and 551 women reported new diagnoses, and 110 men and 187 women reported extractions of cataracts. For both endpoints, a higher vitamin C intake was associated with a reduced incidence of cataracts in both sexes. After adjusting for potential confounding factors, the multivariate odds ratios (ORs) for men and women in the highest quintiles of energy-adjusted vitamin C intake, relative to the lowest quintiles, were 0.65 (95% CI, 0.42-0.97) and 0.59 (95% CI, 0.43-0.89) for cataract diagnoses, and 0.70 (95% CI, 0.44-1.20) and 0.64 (95% CI, 0.41-0.94) for cataract extractions, respectively.
  
  
  CONCLUSIONS
  Dietary vitamin C intake might lower the risk of age-related cataracts among middle-aged Japanese.
authors.affiliation: Dept. of Public Health, Kyorin University School of Medicine, Tokyo, Japan.
authors.forename: Masao
authors.initials: M
authors.lastname: Yoshida
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Takashima
authors.forename: Manami
authors.initials: M
authors.lastname: Inoue
authors.forename: Motoki
authors.initials: M
authors.lastname: Iwasaki
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Otani
authors.forename: Satoshi
authors.initials: S
authors.lastname: Sasaki
authors.forename: Shoichiro
authors.initials: S
authors.lastname: Tsugane
mesh_terms: D000375:Aging; D000975:Antioxidants / Q000008:administration & dosage* / Q000032:analysis; D001205:Ascorbic Acid / Q000008:administration & dosage* / Q000032:analysis; D002386:Cataract / Q000453:epidemiology* / Q000517:prevention & control; D002387:Cataract Extraction; D015331:Cohort Studies; D004032:Diet; D004034:Diet Surveys; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007564:Japan / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016017:Odds Ratio; D015995:Prevalence; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires
chemical_list: D000975:Antioxidants; D001205:Ascorbic Acid