Data from two large studies shows that higher adherence to the Mediterranean diet was associated with a 41% reduced risk of age-related macular degeneration (AMD).
Evidence is mounting that a poor diet plays an important role in the development of age-related macular degeneration (AMD), a leading cause of blindness in the US. A large collaboration of researchers from the EU investigating the connection between genes and lifestyle on the development of AMD has found that people who adhered to a Mediterranean diet cut their risk of late-stage AMD by 41%. This research expands on previous studies and suggests that such a diet is beneficial for everyone, whether you already have the disease or are at risk of developing it.
A Mediterranean diet emphasises eating less meat and more fish, vegetables, fruits, legumes, unrefined grains, and olive oil. Previous research has linked it to a longer lifespan and a reduced incidence of heart disease and cognitive decline. But only a few studies have evaluated its impact on AMD. Some studies showed it can help with certain types of AMD, or only at different stages of the disease.
But combining this earlier research on AMD with the latest data, and a clear picture emerges. Diet has the potential to prevent a blinding disease.
AMD is a degenerative eye disease. It causes loss of central vision, which is crucial for simple everyday activities, such as the ability to see faces, drive, read, and write. It's a leading cause of vision loss among people age 50 and older, affecting 1.8m Americans. By 2020, that number is expected to climb to nearly 3m.
For this latest study, researchers analysed food-frequency questionnaires from nearly 5,000 people who participated in two previous investigations – the Rotterdam Study, which evaluated disease risk in people age 55 and older, and the Alienor Study, which assessed the association between eye diseases and nutritional factors in people aged 73 and older. Patients in the Rotterdam study were examined and completed food questionnaires every five years over a 21-year period, while patients in the Alienor Study were seen every two years over a 4-year period. The researchers found that those who closely followed the diet were 41 percent less likely to develop AMD compared with those who did not follow the diet.
They also found that none of the individual components of a Mediterranean diet on their own – fish, fruit, vegetables, etc – lowered the risk of AMD. Rather, it was the entire pattern of eating a nutrient-rich diet that significantly reduced the risk of late AMD.
"You are what you eat," said Dr Emily Chew, a clinical spokesperson for the American Academy of Ophthalmology, who serves on an advisory board to the research group conducting the study. "I believe this is a public health issue on the same scale as smoking. Chronic diseases such as AMD, dementia, obesity, and diabetes, all have roots in poor dietary habits. It's time to take quitting a poor diet as seriously as quitting smoking."
There are two kinds of AMD – dry and wet. The dry type affects about 80% to 90% of people with AMD. In dry AMD, small white or yellowish deposits, called drusen, form on the retina, causing it to deteriorate over time. In the wet form, blood vessels grow under the retina and leak. While there is an effective treatment available for the wet type, there is no treatment available for dry AMD.
Purpose: To investigate associations of adherence to the Mediterranean diet (MeDi) with incidence of advanced age-related macular degeneration (AMD; the symptomatic form of AMD) in 2 European population-based prospective cohorts.
Design: Prospective cohort study of the Rotterdam Study I (RS-I) and the Antioxydants, Lipides Essentiels, Nutrition et Maladies Oculaires (Alienor) Study populations.
Participants: Four thousand four hundred forty-six participants 55 years of age or older from the RS-I (The Netherlands) and 550 French adults 73 years of age or older from the Alienor Study with complete ophthalmologic and dietary data were included in the present study.
Methods: Examinations were performed approximately every 5 years over a 21-year period (1990–2011) in RS-I and every 2 years over a 4-year period (2006–2012) in the Alienor Study. Adherence to the MeDi was evaluated using a 9-component score based on intake of vegetables, fruits, legumes, cereals, fish, meat, dairy products, alcohol, and the monounsaturated-to-saturated fatty acids ratio. Associations of incidence of AMD with MeDi were estimated using multivariate Cox proportional hazard models.
Main Outcomes Measures: Incidence of advanced AMD based on retinal fundus photographs.
Results: Among the 4996 included participants, 155 demonstrated advanced incident AMD (117 from the RS-I and 38 from the Alienor Study). The mean follow-up time was 9.9 years (range, 0.6–21.7 years) in the RS-I and 4.1 years (range, 2.5–5.0 years) in the Alienor Study. Pooling data for both the RS-I and Alienor Study, participants with a high (range, 6–9) MeDi score showed a significantly reduced risk for incident advanced AMD compared with participants with a low (range, 0–3) MeDi score in the fully adjusted Cox model (hazard ratio, 0.59; 95% confidence interval, 0.37–0.95; P = 0.04 for trend).
Conclusions: Pooling data from the RS-I and Alienor Study, higher adherence to the MeDi was associated with a 41% reduced risk of incident advanced AMD. These findings support the role of a diet rich in healthful nutrient-rich foods such as fruits, vegetables, legumes, and fish in the prevention of AMD.
Bénédicte MJ Merle, Johanna M Colijn, Audrey Cougnard-Grégoire, Alexandra PM de Koning-Backus, Marie-Noëlle Delyfer, Jessica C Kiefte-de Jong, Magda Meester-Smoor, Catherine Féart, Timo Verzijden, Cécilia Samieri, Oscar H Franco, Jean-François Korobelnik, Caroline CW Klaver, Cécile Delcourt, Soufiane Ajana, Blanca Arango-Gonzalez, Angela Armento, Verena Arndt, Vaibhav Bhatia, Shomi S Bhattacharya, Marc Biarnés, Anna Borrell, Sebastian Bühren, Sofia M Calado, Johanna M Colijn, Audrey Cougnard-Grégoire, Sascha Dammeier, Eiko K. de Jong, Berta De la Cerda, Cécile Delcourt, Anneke I den Hollander, Francisco J Diaz-Corrales, Sigrid Diether, Eszter Emri, Tanja Endermann, Lucia L Ferraro, Míriam Garcia, Thomas J Heesterbeek, Sabina Honisch, Carel B Hoyng, Eveline Kersten, Ellen Kilger, Caroline CW Klaver, Hanno Langen, Imre Lengyel, Phil Luthert, Cyrille Maugeais, Magda Meester-Smoor, Bénédicte MJ Merle, Jordi Monés, Everson Nogoceke, Tunde Peto, Frances M Pool, Eduardo Rodríguez, Marius Ueffing, Karl U Ulrich Bartz-Schmidt, Elisabeth M van Leeuwen, Timo Verzijden, Markus Zumbansen, Vassil Vasiliev
[link url="https://www.aao.org/newsroom/news-releases/detail/study-mediterranean-diet-prevents-blindness-cause"]American Academy of Ophthalmology material[/link]
[link url="https://www.aaojournal.org/article/S0161-6420(18)30721-8/abstract"]Ophthalmology journal abstract[/link]