Dietary glycemic index and the risk of age-related macular degeneration.
BACKGROUND
Dietary factors are known risk factors for age-related macular degeneration (AMD) -- the leading cause of visual loss among persons aged > or =65 y. High-glycemic-index diets have been hypothesized as a risk factor for AMD, but prospective data are unavailable.


OBJECTIVE
The objective was to examine the association between dietary glycemic index and the 10-y incidence of AMD in the Blue Mountain Eye Study population.


METHODS
This was a population-based cohort study with 3,654 participants (> or =49 y) examined at baseline (1992-1994); 2,335 patients were reexamined after 5 y and 1952 after 10 y. The Wisconsin System was used to grade 10-y incident early and late AMD from retinal photographs. A food-frequency questionnaire was used to collect dietary information at baseline, and an Australian database was used to calculate the mean glycemic index.


RESULTS
Over 10 y, 208 of 1,810 persons (cumulative incidence: 14.1%) developed early AMD. After age, smoking, other risk factors, and dietary constituents were adjusted for, a higher mean dietary glycemic index was associated with an increased 10-y risk of early AMD in a comparison of quartiles 1 and 4 [relative risk (RR): 1.77; 95% CI: 1.13, 2.78; P for trend = 0.03]. Conversely, a greater consumption of cereal fiber (RR: 0.68; 95% CI: 0.44, 1.04; P for trend = 0.05) and breads and cereals (predominantly lower glycemic index foods such as oatmeal) (RR: 0.67; 95% CI: 0.44, 1.02; P for trend = 0.03) was associated with a reduced risk of incident early AMD. No relation was observed with late AMD.


CONCLUSIONS
A high-glycemic-index diet is a risk factor for early AMD -- the recognized precursor of sight-threatening late AMD. Low-glycemic-index foods such as oatmeal may protect against early AMD.
Kaushik
Shweta
S
Centre for Vision Research, Department of Ophthalmology and Westmead Millennium Institute, University of Sydney, Sydney, Australia.
Wang
Jie Jin
JJ
Flood
Victoria
V
Tan
Jennifer Sue Ling
JS
Barclay
Alan W
AW
Wong
Tien Y
TY
Brand-Miller
Jennie
J
Mitchell
Paul
P
D000368:Aged; D015331:Cohort Studies; D004040:Dietary Carbohydrates / Q000008:administration & dosage* / Q000145:classification / Q000378:metabolism; D004043:Dietary Fiber / Q000008:administration & dosage* / Q000145:classification / Q000378:metabolism; D005247:Feeding Behavior; D005260:Female; D005500:Follow-Up Studies; D038321:Glycemic Index; D006801:Humans; D015994:Incidence; D008268:Macular Degeneration / Q000453:epidemiology* / Q000209:etiology / Q000517:prevention & control; D008297:Male; D008875:Middle Aged; D015999:Multivariate Analysis; D009517:New South Wales / Q000453:epidemiology; D011446:Prospective Studies; D012307:Risk Factors; D011795:Surveys and Questionnaires
D004040:Dietary Carbohydrates; D004043:Dietary Fiber