A Mediterranean diet was associated with slower geographic atrophy (GA) enlargement, suggesting dietary patterns may be linked to clinically meaningful delays in vision loss.
New findings from a post-hoc analysis of a cohort within the Age-Related Eye Disease Study indicate several components may contribute most to the association in a pattern that differed from those most associated with decreased progression to GA.
Study investigators noted the enlargement was slower in people with higher whole fruit, lower red meat, moderate alcohol, and higher monounsaturated fatty acid to saturated fatty acid ratio intake.
“Hence, the Mediterranean diet is associated with protection against both faster progression to GA and faster enlargement of GA but for partially distinct reasons,” wrote corresponding author Tiarnan D. L. Keenan, MD, PhD, Division of Epidemiology and Clinical Applications, National Eye Institute, National Institutes of Health. “These findings may help inform evidence-based dietary recommendations.”
Keenan and colleagues set out to determine the level of adherence to the diet necessary to alter the speed of GA enlargement. They included 1155 eyes from 850 participants (mean age, 74.9 years) with GA at 2 or more visits.
The GA 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.
The mixed-model regression of square root GA area was performed by aMedi. Main outcomes for the study consisted of the change in square root of GA area over time.
A mean follow-up of 3.1 years revealed the mean GA enlargement rate was 0.282 mm/year (95% confidence interval [CI], 0.270 – 0.293).
The data show 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 = .008) for aMedi tertiles 3, 2, and 1, respectively.
From 9 aMedi components, each considered separately, significant differences in enlargement rate were observed for 4 (whole fruit [P = .0004], red meat [P = .0002], alcohol [P = .006], and monounsaturated fatty acid to saturated fatty acid ratio [P = .040]). It was not observed for fish (P = .14).
For the 768 eyes with noncentral GA, aMedi was not associated with slower progression to central involvement. Data show the hazard ratios were 1.11 (95% CI, 0.83 – 1.48) and 0.95 (95% CI, 0.71 – 1.26) for teriles 2 and 3, respectively.
“Understanding the mechanisms responsible may provide insights into the underlying biology and lead to the development of nutritional supplements,” Keenan added.
The study, “Adherence to a Mediterranean Diet and Geographic Atrophy Enlargement Rate: Age-Related Eye Disease Study 2 Report 29,” was published in Ophthalmology Retina.