Mediterranean Diet Shows Benefits for Slowing Age-Related Macular Degeneration Progression

AMD affects many older adults in high-income countries, with limited options to manage its progression, especially for early and intermediate stages. Smoking is recognized as the primary modifiable risk factor, and diet has emerged as a significant factor influencing AMD progression. Notably, the Mediterranean diet stands out among various dietary patterns for its beneficial effects on aging and chronic disease outcomes, focusing on vegetables, fruits, whole grains, nuts, moderate fish consumption, low red meat intake, and reduced refined sugar.

Researchers from the National Eye Institute (NEI) and the University of Michigan conducted a targeted review to understand dietary impacts on AMD progression. The review pulled data mainly from the Age-Related Eye Disease Studies (AREDS and AREDS2) conducted in the U.S., as well as significant European and North American epidemiological studies.

Adherence to the Mediterranean diet was measured using the Alternative Mediterranean Diet Index (aMED), which assesses consumption of various food groups. The findings indicate that stronger adherence to this diet correlates with a significantly slower progression of AMD across different disease stages. For early AMD, participants in the highest aMED tertile had a 21% lower likelihood of developing large drusen compared to those in the lowest tertile. In intermediate AMD, those in the top aMED category were 23% less likely to progress to late AMD, with a stronger protective effect against geographic atrophy (GA) at 29% than neovascular AMD at 16%. For GA, those adhering closely to the Mediterranean diet showed approximately 15% slower enlargement rates.

Detailed analysis of specific food components revealed that for intermediate AMD, fish consumption was particularly protective, leading to a 31% decreased risk of transitioning to late AMD. Higher vegetable intake also provided a 23% lower risk, whereas increased red meat consumption correlated with a 20% higher risk. In terms of GA enlargement, greater whole fruit intake led to a 22% slower progression, while lower red meat intake resulted in a 23% decrease in enlargement speed. Additionally, a higher ratio of monounsaturated to saturated fats and less alcohol consumption contributed to slower GA progression.

For patients taking dietary supplements, the AREDS2 formulation, which includes vitamins C, E, zinc, copper, and lutein/zeaxanthin, significantly reduced the risk of advancing to advanced AMD, largely by lowering neovascular AMD risk. In those with GA, supplements slowed the progression toward the fovea by about 50%. This suggests that diet and supplements may work through different mechanisms, highlighting the importance of combining both strategies.

Limitations of the review included its selective nature rather than being exhaustive, primarily relying on observational data. Many findings related to GA stemmed from post-hoc analyses rather than dedicated trials, and the dietary habits of the study populations were generally healthier than the average in the U.S., which might affect the perceived impact of supplementation.

The authors emphasized that the principles of the Mediterranean diet can be adapted to various cultural diets, suggesting that even minor dietary changes can yield significant benefits. A noteworthy finding indicated that adherence to a healthy lifestyle—including the Mediterranean diet—can reduce the risk of AMD progression by three to five times, even among individuals with a high genetic predisposition to the disease.

Despite the clear benefits of a Mediterranean diet, actual adherence in the general population is low; for example, a study found only 4% of adults met recommended intakes for vegetables, fruits, and fish. This gap presents an opportunity for clinicians to engage patients during critical discussions about AMD management.

In conclusion, all patients with AMD should be encouraged to embrace a Mediterranean-style diet, adjusting food emphasis based on disease stage. High fish intake is crucial for intermediate AMD, while a focus on diverse fruits and vegetables along with reduced red meat is key for GA management. Supplements from the AREDS2 formulation should complement, rather than replace, dietary changes.