Mediterranean Diet May Deter Macular Degeneration

Published this November in Ophthalmology, a recent study joins an ever-deepening well of data vouching for the health benefits of the Mediterranean diet. The diet is usually identified as being high in fish, fruit, and grains, low in saturated fat and sweeteners, and containing a tasteful splash of wine and coffee.

Another eye study presented in Chicago at the American Academy of Ophthalmology meeting Chicago examined a population of Portuguese patients found strong adherence to the diet to be protective for age-related macular degeneration (AMD), namely correlating Vitamins C and E as well as caffeine with decreased risk of developing the condition. Different studies have attempted to link the diet to improvements in everything from heart disease to multiple sclerosis.

This recent study examined over 5,000 people from across Europe, including French, Italian, Norwegian, Spanish, British, Estonian, and Greek participants. At baseline they each underwent a graded eye examination and digital retinal color photography, and answered a food-frequency questionnaire that allowed the researchers to assign them a Mediterranean Diet Score (MDS) based on their adherence over the previous 12 months. The 0-9 point scale was based on a point assigned for one or more defined unit per day or week of olive oil, wine, fruit, vegetables, fish, and legumes, with one added each for low consumption of white bread, meat products, and rice.

The fundus images were all sent to a single center, Erasmus University in Rotterdam, for reading and grading. Grade 0 referred to a macula free of drusen or pigmentary irregularities, or with only hard drusen; grades 1 and 2 consisted of early AMD patients depending on degree of pigmentary abnormalities and soft distinct or indistinct druse; grade 3 were cases with more significant soft indistinct drusen or reticular drusen with pigmentary abnormalities; and grade 4 encompassed the presence of neovascular AMD (nvAMD) including serous or hemorrhagic retinal or retinal pigment epithelial detachment, subretinal vascular membrane, periretinal fibrous scar, or geographic atrophy (GA). Blood samples were also collected at baseline.

Average age of the participants was 73.2 years old, with a small majority being female (55%). Diet adherence scores were, perhaps predictably, higher in the nations closest to the Mediterranean: Italian participants’ MDS average was 5.72, followed by Spain at 5.32, Greece at 5.19, Norway at 4.89 (the one exception to that proximity), France at 4.62, Estonia at 4.49, and the UK at 4.42.

Analysis showed what the researchers called a “weak trend from no AMD to late AMD: AMD 0 5.03 (4.6-5.5), AMD 1 5.02 (4.6-5.4), AMD 2 5.08, 4.7-5.5) AMD 3 4.97 (4.5-5.5), AMD 4 4.76 (4.3-5.2), p for trend = 0.16.” Those in the highest bracket of diet scores had a 20% reduced risk of large drusen compared to those in the lowest adherence bracket.

The authors acknowledged the drawbacks of basing data on self-reported questionnaires, but argue that their work contributes to a small-but-growing evidence base of the way the Mediterranean diet can combat AMD, which is the leading cause of blindness in the developed world.

“Interventions to encourage the adoption of the Mediterranean diet more widely should be developed,” they conclude, “while methods by which such behavior change can be achieved and maintained over the long term should be investigated.”

The study was led by Ruth E. Hogg as part of the European Eye Study. It was published online on November 5^th.

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