Lutein and Zeaxanthin and Age–Related Macular Degeneration in the Melbourne Visual Impairment Project

Abstract

Abstract: : Purpose: To evaluate the association of early and/or late age–related macular degeneration (AMD) with dietary intake of lutein/zeaxanthin (LZ) in the population–based sample of the Melbourne Visual Impairment Project. Methods: Permanent residents aged 40 years and older were recruited via a household census using cluster stratified sampling. All available baseline (1992–1994) participants were re–examined in 1997–1999. Follow–up examination included macular stereo photography and extensive food frequency (FFQ) and lifestyle questionnaires. We obtained from the logistic regressions the odds ratios adjusted by age (years), and cigarette smoking duration (>40 years versus ≤40 years) for the daily LZ intake, its squared value, or its quintile indicator with the lowest quintile as the basline category. Results: Of the 2594 participants who attended the follow up examination, 2143 (83%) had a complete record for smoking duration, dietary intake and either clinical or photographic assessment. There were 38 (1.8%) prevalent late cases, and 450 (21%) or 157 (7.3%) prevalent early cases according to the international classification (IC) or Blue Mountains Eye Study (BMES) definitions respectively. The initial analyses found no association of daily LZ intake when examined as a continuous variable or by quintiles, and the lowest odds ratios (95% CI) for those in the second quintiles were 0.80 (0.58–1.12) for any IC AMD, 0.80 (0.57–1.12) for early IC AMD, 0.76 (0.47–1.22) for any BMES AMD, and 0.72 (0.43–1.20) for early BMES AMD. The upward quadratic trends were significant for any or early IC AMD (p = 0.05) with the turning points x₀ corresponding to the lowest risk of daily LZ intake in the second quintiles. These trends showed some protective effect for daily LZ intake < x₀, and harmful effect for daily LZ intake > x₀. When daily LZ intake was adjusted by total energy intake, a higher intake significantly increased the risks of developing any or early AMD in continuous and quintile analyses. The highest odds ratios for those in the top quintiles were 1.44 (1.04–1.98) for any IC AMD, and 1.41 (1.02–1.95) for early IC AMD. The upward quadratic trends were significant for any or early IC AMD (p = 0.01), any BMES AMD (p = 0.04), and early BMES AMD (p = 0.02) with x₀’s in the second quintiles. Conclusions: This study showed a possible protective and also a possibly deleterious role of daily intake of LZ. Further studies are clearly needed to elucidate this complex relationship.

Keywords: age-related macular degeneration • clinical (human) or epidemiologic studies: risk factor assessment