title: Blood levels of vitamin C, carotenoids and retinol are inversely associated with cataract in a North Indian population.
abstract: OBJECTIVE
  To examine the association of blood antioxidants with cataract.
  
  
  METHODS
  Cross-sectional study of people aged >or=50 years identified from a household enumeration of 11 randomly sampled villages in North India. Participants were interviewed for putative risk factors (tobacco, alcohol, biomass fuel use, sunlight exposure, and socioeconomic status) and underwent lens photography and blood sampling. Lens photographs (nuclear, cortical, and posterior subcapsular) were graded according to the Lens Opacities Classification System (LOCS II). Cataract was defined as LOCS II grade >or=2 for any opacity or ungradable, because of dense opacification or history of cataract surgery. People without cataract were defined as LOCS II <2 on all three types of opacity, with absence of previous surgery.
  
  
  RESULTS
  Of 1443 people aged >or=50 years, 94% were interviewed, 87% attended an eye examination, and 78% gave a blood sample; 1112 (77%) were included in the analyses. Compared with levels in Western populations, antioxidants were low, especially vitamin C. Vitamin C was inversely associated with cataract. Odds ratios (OR) for the highest (>or=15 micromol/L) compared with the lowest (<or=6.3 micromol/L) tertile were 0.64, (95% confidence interval [CI] 0.48-0.85; P < 0.01). Tertiles of zeaxanthin (P < 0.03), alpha-carotene (P < 0.05), and retinol (P < 0.02) were associated with decreased odds of cataract. In analysis of continuous data, significant inverse associations were found for vitamin C, zeaxanthin, lutein, lycopene, alpha- and beta-carotene, and beta-cryptoxanthin, but not for alpha- or gamma-tocopherol.
  
  
  CONCLUSIONS
  Inverse associations were found between cataract and blood antioxidants in an antioxidant-depleted study sample.
authors.affiliation: Department of Epidemiology and Population Health, London School of Hygiene and Tropical Medicine, London, United Kingdom.
authors.forename: Mukesh
authors.initials: M
authors.lastname: Dherani
authors.forename: Gudlavalleti V S
authors.initials: GV
authors.lastname: Murthy
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: Gill M
authors.initials: GM
authors.lastname: Price
authors.forename: Neena
authors.initials: N
authors.lastname: John
authors.forename: Usha
authors.initials: U
authors.lastname: Chakravarthy
authors.forename: Astrid E
authors.initials: AE
authors.lastname: Fletcher
mesh_terms: D000368:Aged; D001205:Ascorbic Acid / Q000097:blood*; D001824:Body Constitution; D002338:Carotenoids / Q000097:blood*; D002386:Cataract / Q000097:blood* / Q000175:diagnosis / Q000208:ethnology; D002851:Chromatography, High Pressure Liquid; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D007194:India / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D016017:Odds Ratio; D010781:Photography; D012307:Risk Factors; D012424:Rural Population / Q000706:statistics & numerical data; D011795:Surveys and Questionnaires; D014801:Vitamin A / Q000097:blood*
chemical_list: D014801:Vitamin A; D002338:Carotenoids; D001205:Ascorbic Acid