Adherence to a Mediterranean Diet and Geographic Atrophy Enlargement Rate: Age-Related Eye Disease Study 2 Report 29.

purposeTo determine whether closer adherence to a Mediterranean diet was associated with altered speed of geographic atrophy (GA) enlargement.

designPost hoc analysis of a cohort within the Age-Related Eye Disease Study 2.

participantsThe study included 1155 eyes (850 participants; mean age, 74.9 years) with GA at 2 or more visits.

methodsGeographic atrophy area was measured from color fundus photographs at annual visits. An alternative Mediterranean Diet index (aMedi) was calculated for each participant by food frequency questionnaire. Mixed-model regression of square root GA area was performed by aMedi.

main outcome measuresChange in square root of GA area over time.

resultsOver a mean follow-up of 3.1 years, the mean GA enlargement rate was 0.282 mm/year (95% confidence interval, 0.270-0.293). Enlargement was significantly slower in those with higher aMedi at 0.256 mm/year (0.236-0.276), 0.290 (0.268-0.311), and 0.298 (0.280-0.317; P = 0.008) for aMedi tertiles 3, 2, and 1, respectively. Of the 9 aMedi components considered separately, significant differences in enlargement rate were observed for 4 (whole fruit [P = 0.0004], red meat [P = 0.0002], alcohol [P = 0.006], and monounsaturated fatty acid to saturated fatty acid ratio ([MUFA:SFA] [P = 0.040]) but not for fish (P = 0.14). Enlargement was slower in those with higher whole fruit, lower red meat, moderate alcohol, and higher MUFA:SFA intake. In the 768 eyes with noncentral GA, aMedi was not associated with slower progression to central involvement: hazard ratios were 1.11 (0.83-1.48) and 0.95 (0.71-1.26) for tertiles 2 and 3, respectively.

conclusionsA Mediterranean-type diet was associated with slower GA enlargement. Diet patterns like this may therefore lead to clinically meaningful delays in vision loss. Several components seemed to contribute most to this association in a pattern that differed from those most associated with decreased progression to GA. Hence, the Mediterranean diet is associated with protection against both faster progression to GA and faster enlargement of GA but for partially distinct reasons. These findings may help inform evidence-based dietary recommendations. Understanding the mechanisms responsible may provide insights into the underlying biology and lead to the development of nutritional supplements.