title: Inverse association of vitamin C with cataract in older people in India.
abstract: OBJECTIVE
  To examine the association between vitamin C and cataract in the Indian setting.
  
  
  METHODS
  Population-based cross-sectional analytic study.
  
  
  METHODS
  A total of 5638 people aged ≥60 years.
  
  
  METHODS
  Enumeration of randomly sampled villages in 2 areas of north and south India to identify people aged ≥60 years. Participants were interviewed for socioeconomic and lifestyle factors (tobacco, alcohol, household cooking fuel, work, and diet); attended a clinical examination, including lens photography; and provided a blood sample for antioxidant analysis. Plasma vitamin C was measured using an enzyme-based assay in plasma stabilized with metaphosphoric acid, and other antioxidants were measured by reverse-phase high-pressure liquid chromatography.
  
  
  METHODS
  Cataract and type of cataract were graded from digital lens images using the Lens Opacity Classification System III (LOCS III), and cataract was classified from the grade in the worse eye of ≥4 for nuclear cataract, ≥3 for cortical cataract, and ≥2 for posterior subcapsular cataract (PSC). Any cataract was defined as any unoperated or operated cataract.
  
  
  RESULTS
  Of 7518 enumerated people, 5638 (75%) provided data on vitamin C, antioxidants, and potential confounders. Vitamin C was inversely associated with cataract (adjusted odds ratio [OR] for highest to lowest quartile = 0.61; 95% confidence interval (CI), 0.51-0.74; P=1.1×10(-6)). Inclusion of other antioxidants in the model (lutein, zeaxanthin, retinol, β-carotene, and α-tocopherol) made only a small attenuation to the result (OR 0.68; 95% CI, 0.57-0.82; P < 0.0001). Similar results were seen with vitamin C by type of cataract: nuclear cataract (adjusted OR 0.66; CI, 0.54-0.80; P < 0.0001), cortical cataract (adjusted OR 0.70; CI, 0.54-0.90; P < 0.002), and PSC (adjusted OR 0.58; CI, 0.45-0.74; P < 0.00003). Lutein, zeaxanthin, and retinol were significantly inversely associated with cataract, but the associations were weaker and not consistently observed by type of cataract. Inverse associations were also observed for dietary vitamin C and cataract.
  
  
  CONCLUSIONS
  We found a strong association with vitamin C and cataract in a vitamin C-depleted population.
  
  
  BACKGROUND
  The author(s) have no proprietary or commercial interest in any materials discussed in this article.
authors.affiliation: Aravind Eye Hospital Pondicherry, Aravind Eye Care, Pondicherry, India.
authors.forename: Ravilla D
authors.initials: RD
authors.lastname: Ravindran
authors.forename: Praveen
authors.initials: P
authors.lastname: Vashist
authors.forename: Sanjeev K
authors.initials: SK
authors.lastname: Gupta
authors.forename: Ian S
authors.initials: IS
authors.lastname: Young
authors.forename: Giovanni
authors.initials: G
authors.lastname: Maraini
authors.forename: Monica
authors.initials: M
authors.lastname: Camparini
authors.forename: R
authors.initials: R
authors.lastname: Jayanthi
authors.forename: Neena
authors.initials: N
authors.lastname: John
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Fitzpatrick
authors.forename: Usha
authors.initials: U
authors.lastname: Chakravarthy
authors.forename: Thulasiraj D
authors.initials: TD
authors.lastname: Ravilla
authors.forename: Astrid E
authors.initials: AE
authors.lastname: Fletcher
mesh_terms: D000368:Aged; D000975:Antioxidants / Q000378:metabolism; D001205:Ascorbic Acid / Q000097:blood*; D001206:Ascorbic Acid Deficiency / Q000097:blood / Q000453:epidemiology*; D002386:Cataract / Q000097:blood / Q000145:classification / Q000453:epidemiology*; D002851:Chromatography, High Pressure Liquid; D003430:Cross-Sectional Studies; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007194:India / Q000453:epidemiology; D014975:Lutein / Q000097:blood; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D024341:Xanthophylls / Q000097:blood; D065146:Zeaxanthins; D024502:alpha-Tocopherol / Q000097:blood; D019207:beta Carotene / Q000097:blood
chemical_list: D000975:Antioxidants; D024341:Xanthophylls; D065146:Zeaxanthins; D019207:beta Carotene; D024502:alpha-Tocopherol; D001205:Ascorbic Acid; D014975:Lutein