Abstract
Purpose::
Cross-sectional studies indicate that diets that provide a higher dietary glycemic index (dGI) are associated with increased risk of age-related macular degeneration (AMD).1, 2 No prospective studies have addressed this issue.
Methods::
Dietary information was obtained from 3977 participants aged 55 - 80 y (58% female) in the Age-Related Eye Disease Study (AREDS). dGI was calculated as the weighted average of foods3 and evaluated as being above or below the gender median (female = 77.9, male = 79.3). Eyes with advanced AMD (neovascular or central geographic atrophy) at baseline were considered as not at risk of further progression and excluded. The 7232 eligible eyes at risk of progression were classified into one of three AMD categories: Group 1 (no drusen/nonextensive small drusen), 2 (intermediate drusen/extensive small drusen/pigmentary abnormalities), and 3 (large drusen/extensive intermediate drusen) according to the AREDS AMD Classification System. To evaluate the relationship between dGI and AMD progression we modeled the time to the maximal progression of studied eyes by multifailure Cox proportional-hazards models.
Results::
During up to 8 years of follow-up (mean = 5.4 y), overall the multivariate-adjusted risk of progression was significantly higher (risk ratio = 1.10; 95% confidence interval, 1.00, 1.20; P = 0.047) in the high dGI vs. the low dGI group. The increased risk of progression for Group 1, 2, and 3 eyes was 5%, 8%, and 17%, respectively. The 17% increased risk of developing advanced AMD for people with high dGI and at high risk of progression to advanced AMD gives a population attributable proportion of 7.8%. This allows an estimate that over 100,000 cases of advanced AMD and any accompanying vision loss could be eliminated in the US during the next 5 y if people aged 55+ y consumed diets which have dGI values below the median.
Conclusions::
These data suggest that there is a benefit of consuming less refined carbohydrates in persons at risk of AMD progression, especially for those at high risk for advanced AMD. References 1. Chiu CJ, Hubbard LD, Armstrong J, et al. Am J Clin Nutr 2006;83:880-6. 2. Chiu CJ, Milton RC, Gensler G, Taylor A. Am J Clin Nutr (in revision) 2006. 3. Wolever TM, Nguyen PM, Chiasson JL, et al. Am J Clin Nutr 1994;59:1265-9.
Keywords: age-related macular degeneration • clinical (human) or epidemiologic studies: risk factor assessment • glycoconjugates/glycoproteins