Age-related macular degeneration (AMD) is the leading cause of severe central vision loss and legal blindness in the population over 60 years of age. It is a disease that results from a complex interaction between several factors, such as ageing, genetic predisposition, environmental factors and pre-existing pathologies, such as diabetes.
Late AMD, the disease condition most associated with the risk of blindness, occurs in two forms: geographic atrophy (GA) and neovascular AMD. Neovascular AMD is currently treated with intravitreal injections, which must be repeated over time, of anti-VEGF drugs, whereas no treatment is currently available for GA. For this very reason, preventive approaches can be very useful for both subtypes of late disease.
It is known that taking food supplements with specific combinations of antioxidants and minerals can decrease the risk of progression from intermediate to late age-related macular degeneration, particularly in the case of the neovascular form. In addition, observational studies have shown that a higher intake of specific nutrients is associated with a change in the risk of developing AMD. In particular, it has been observed that a reduced risk of progression of age-related macular degeneration is associated with a higher intake of omega-3 fatty acids and carotenoids (lutein and zeaxanthin), taken either through diet or supplements.
Two recent studies, conducted on more than 8,000 patients, have shown that the adoption of a Mediterranean diet, and in particular its fish component, is strongly associated with a decrease in progression to late AMD, particularly to geographic atrophy.
Foods that reduce the risk of ELM progression
Several nutrients have been associated with a lower risk of ELM progression. These are, in particular, long-chain polyunsaturated fatty acids (LC-PUFA), omega-3, minerals (e.g. copper, magnesium and selenium), B vitamins and antioxidant carotenoids (e.g, β-carotene and lutein/zeaxanthin). It appears, therefore, that a Mediterranean-type diet or the intake of certain individual food components may play an important part in counteracting the progression of this disease.
Fish consumption is thought to play a key role. The intake of LC-PUFA and omega-3 has, in fact, been correlated with a lower risk of AMD progression, as has also been found in many studies published in the literature. The reason is that these two types of nutrients produce anti-inflammatory and anti-angiogenic metabolites.
Fish also contains large amounts of B vitamins, the intake of which has been associated with a 34% reduction in the incidence of AMD. A possible mechanism by which an adequate intake of folic acid and vitamins B6 and B12 would protect against AMD could be the prevention of increased serum homocysteine. The latter, in high amounts, is in fact an independent risk factor for neurodegenerative and cardiovascular diseases and has also been associated with AMD.
Certain minerals contained in fish, including copper, iron, magnesium and selenium, may also reduce the risk of ELD progression.
Not only fish, but also fruit and vegetables contain abundant amounts of antioxidant nutrients, which are associated with a decreased risk of ELM progression. These include vitamin C, pro-vitamin A carotenoids (α-carotene, β-carotene and β-cryptoxanthin) and lutein/zeaxanthin.
Foods that may increase the risk of ELM progression
A higher intake of certain nutrients seems, on the other hand, to be associated with an increased risk of late AMD progression. These are, in particular, unsaturated and monounsaturated fats and oleic acid. The primary sources of unsaturated and monounsaturated fats are meat, dairy products and sugary, high-fat, low-nutrient-density foods.
In conclusion, increased dietary intake of certain types of nutrients is associated with a reduced risk of AMD progression, including: minerals, vitamins and carotenoids. This positive association applies to both subtypes of late-stage AMD, but is particularly evident for geographic atrophy, for which no treatment is currently available. These nutrients can also be taken through dietary supplementation. Diet and oral supplementation can, therefore, play complementary roles in reducing the risk of progression of age-related macular degeneration.
Bibliography
Elvira Agrón et al, Dietary Nutrient Intake and Progression to Late Age-Related Macular Degeneration in the Age-Related Eye Disease Studies 1 and 2, VOLUME 128, ISSUE 3, P425-442, MARCH 01, 2021, DOI:https://doi.org/10.1016/j.ophtha.2020.08.018
Dr. Carmelo Chines
Direttore responsabile
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