Prospective study showing that dietary vitamin C reduced the risk of age-related cataracts in a middle-aged Japanese population

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. Aim of the study 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. Conclusion Dietary vitamin C intake might lower the risk of age-related cataracts among middle-aged Japanese.