Dietary carbohydrate and the progression of age-related macular degeneration: a prospective study from the Age-Related Eye Disease Study.
BACKGROUND
Cross-sectional studies indicate that diets that provide a higher dietary glycemic index (dGI) are associated with a greater risk of age-related macular degeneration (AMD). No prospective studies have addressed this issue.


OBJECTIVE
The objective was to prospectively evaluate the effect of baseline dGI on the progression of AMD.


METHODS
dGI was calculated as the weighted average of GIs from foods and was evaluated as being above or below the sex median (women: 77.9; men: 79.3) for 3977 participants aged 55-80 y (58% women) in the Age-Related Eye Disease Study. The 7232 eligible eyes without advanced AMD were classified into 1 of 3 AMD categories: group 1 (nonextensive small drusen), group 2 (intermediate drusen, extensive small drusen, or pigmentary abnormalities), or group 3 (large drusen or extensive intermediate drusen). With the use of multifailure Cox proportional-hazards regression, we modeled the time to the maximal progression to evaluate the relation between dGI and the risk of AMD.


RESULTS
Overall, the multivariate-adjusted risk of progression over 8 y of follow-up (x: 5.4 y) was significantly higher (risk ratio: 1.10; 95% CI: 1.00, 1.20; P = 0.047) in the high-dGI group than in the low-dGI group. The risk of progression for groups 1, 2, and 3 eyes was 5%, 8%, and 17% greater, respectively (P for trend < 0.001). The latter gives an estimate that 7.8% of new advanced AMD cases would be prevented in 5 y if people consumed the low-dGI diet.


CONCLUSIONS
Persons at risk of AMD progression, especially those at high risk of advanced AMD, may benefit from consuming a smaller amount of refined carbohydrates.
Chiu
Chung-Jung
CJ
Jean Mayer US Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, Boston, MA 02111, USA.
Milton
Roy C
RC
Klein
Ronald
R
Gensler
Gary
G
Taylor
Allen
A
D000368:Aged; D000369:Aged, 80 and over; D003430:Cross-Sectional Studies; D004034:Diet Surveys; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000009:adverse effects / Q000145:classification / Q000378:metabolism*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D038321:Glycemic Index; D006801:Humans; D008268:Macular Degeneration / Q000453:epidemiology* / Q000378:metabolism* / Q000473:pathology; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D016016:Proportional Hazards Models; D011446:Prospective Studies; D015593:Retinal Drusen / Q000453:epidemiology / Q000378:metabolism / Q000473:pathology; D012307:Risk Factors; D011795:Surveys and Questionnaires
D004040:Dietary Carbohydrates