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.

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.