Dietary macronutrient intake and five-year incident cataract: the blue mountains eye study

PURPOSE: To investigate the relationships between dietary macronutrient intake at baseline and the five-year incidence of the three main types of cataract in older people. DESIGN: Population-based cohort study. METHODS: Settings: An urban community near Sydney, Australia. STUDY POPULATION: The Blue Mountains Eye Study (BMES) examined 3,654 predominantly Caucasian participants aged 49+ years during 1992 to 1994, and then 2,335 survivors (71.5%) after five years. Of these 2,335 subjects, 1988 (85%) completed a Willett-derived food frequency questionnaire (FFQ) at baseline. OBSERVATION PROCEDURES: A 145-item FFQ was used to assess nutrient intakes and lens photography was used to assess the presence of cataract at both time points. MAIN OUTCOME MEASURES: Incidence of cortical, nuclear, and posterior subcapsular (PSC) cataract was assessed via lens photographic grading following the Wisconsin cataract grading method. RESULTS: After adjusting for multiple known cataract risk factors, higher dietary intakes of omega-3 polyunsaturated fatty acids (n-3 PUFA) were associated with a reduced incidence of nuclear cataract. The odds ratio (OR) for subjects in the highest quintile of intake compared to those in the lowest quintile was 0.58 (95% confidence interval CI] 0.35 to 0.97), P(trend) = .027. Similarly, for PSC cataract, higher dietary intakes of protein were protective (OR 0.28; 95% CI 0.10 to 0.76), P(trend) = .015. Dietary macronutrient intake was not associated with incident cortical cataract. CONCLUSIONS: Higher dietary intakes of n-3 PUFA may decrease the five-year risk of nuclear cataract, whereas higher dietary intakes of protein may decrease risk for PSC cataract.