Dietary antioxidants and the long-term incidence of age-related macular degeneration: the Blue Mountains Eye Study.

PURPOSE

To assess the relationship between baseline dietary and supplement intakes of antioxidants and the long-term risk of incident age-related macular degeneration (AMD).

DESIGN

Australian population-based cohort study.

PARTICIPANTS

Of 3654 baseline (1992-1994) participants initially 49 years of older, 2454 were reexamined after 5 years, 10 years, or both.

METHODS

Stereoscopic retinal photographs were graded using the Wisconsin Grading System. Data on potential risk factors were collected. Energy-adjusted intakes of alpha-carotene; beta-carotene; beta-cryptoxanthin; lutein and zeaxanthin; lycopene; vitamins A, C, and E; and iron and zinc were the study factors. Discrete logistic models assessed AMD risk. Risk ratios (RRs) and 95% confidence intervals (CIs) were calculated after adjusting for age, gender, smoking, and other risk factors.

MAIN OUTCOME MEASURES

Incident early, late, and any AMD.

RESULTS

For dietary lutein and zeaxanthin, participants in the top tertile of intake had a reduced risk of incident neovascular AMD (RR, 0.35; 95% CI, 0.13-0.92), and those with above median intakes had a reduced risk of indistinct soft or reticular drusen (RR, 0.66; 95% CI, 0.48-0.92). For total zinc intake the RR comparing the top decile intake with the remaining population was 0.56 (95% CI, 0.32-0.97) for any AMD and 0.54 (95% CI, 0.30-0.97) for early AMD. The highest compared with the lowest tertile of total beta-carotene intake predicted incident neovascular AMD (RR, 2.68; 95% CI, 1.03-6.96; P = 0.029, for trend). Similarly, beta-carotene intake from diet alone predicted neovascular AMD (RR comparing tertile 3 with tertile 1, 2.40; 95% CI, 0.98-5.91; P = 0.027, for trend). This association was evident in both ever and never smokers. Higher intakes of total vitamin E predicted late AMD (RR compared with the lowest tertile, 2.83; 95% CI, 1.28-6.23; and RR, 2.55; 95% CI, 1.14-5.70 for the middle and highest tertiles, respectively; P = 0.22, for trend).

CONCLUSIONS

In this population-based cohort study, higher dietary lutein and zeaxanthin intake reduced the risk of long-term incident AMD. This study confirmed the Age-Related Eye Disease Study finding of protective influences from zinc against AMD. Higher beta-carotene intake was associated with an increased risk of AMD.