Blood levels of vitamin C, carotenoids and retinol are inversely associated with cataract in a north Indian population

PURPOSE. To examine the association of blood antioxidants with cataract. METHODS. Cross-sectional study of people aged >= 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 >= 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 >= 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 (>= 15 mu mol/L) compared with the lowest (<= 6.3 mu mol/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.