Increased vitamin, mineral intake may hinder late AMD progression
Increased nutrient consumption may be beneficial in decreasing risk for late age-related macular degeneration, according to findings published in Ophthalmology.
Elvira Agrón, MA, and colleagues sought to analyze associations between dietary intake of multiple nutrients and risk for progression to late AMD and its subtypes. An additional objective was to analyze progression to large drusen as well as interactions with AMD genotype.
“Oral supplementation with specific combinations of antioxidants and minerals is known to decrease progression from intermediate to late AMD, particularly neovascular AMD,” Agrón, of the National Eye Institute’s division of epidemiology and clinical applications, and colleagues wrote. “However, it is possible that alternative or additional protection against progression to late AMD may be derived from specific nutrients or other bioactive in food, which may comprise additional modifiable risk factors for AMD.”
The researchers evaluated post hoc analysis of two controlled clinical trial cohorts: Age-Related Eye Disease Study (AREDS) and AREDS2.
Agrón and colleagues identified 14,135 eyes of participants with no late AMD (mean age = 71 years; 56.5% women). The analysis comprised 4,504 participants from the AREDS study and 3,738 participants in the AREDS2 trial.
Fundus photographs were collected at annual study visits and were graded centrally for late AMD, the researchers wrote. Dietary intake of multiple nutrients was calculated for each participant from food frequency questionnaires.
The main outcomes, Agrón and colleagues wrote, were progression in late AMD, geographic atrophy, neovascular AMD and large drusen.
During a median follow up of 10.2 years, the researchers found 32.7% of the eyes progressed to late AMD.
The investigators reported that for nine nutrients, intake quintiles 4 or 5 were significantly associated with decreased risk for late AMD: vitamins A, B6 and C, beta carotene, lutein/zeaxanthin, magnesium, copper and alcohol. Three nutrients in quintiles 4 or 5 — saturated fatty acid, monosaturated fatty acid and oleic acid — were significantly associated with increased risk.
They observed similar results for geographic atrophy. For neovascular AMD, nine nutrients were nominally associated with decreased risk: vitamins A and B6, beta carotene, lutein/zeaxanthin, magnesium, copper, docosahexaenoic acid, omega-3 fatty acid and alcohol. Saturated fatty acid, monosaturated fatty acid and oleic acid were nominally associated.
In separate analyses, investigators reported 12 nutrients were nominally associated with decreased risk for large drusen (n = 5,399 eyes of 3,164 AREDS participants).
“Strong genetic interactions exist for some nutrient-genotype combinations, particularly omega-3 fatty acids and CFH,” Agrón and colleagues wrote. “These data may justify further research into underlying mechanisms and randomized trials of supplementation.”
Perspective
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This article gives some practical information that the clinician can use to counsel patients with AMD about how they can change their diet to decrease the risk of progression to late AMD. The study shows that higher dietary intake of multiple nutrients was associated with decreased risk of late AMD, while other nutrients were associated with increased risk. Further, the results were much greater with dry AMD and geographic atrophy vs. neovascular AMD. Lastly, the study also seemed to indicate strong genetic interactions with some nutrient-genotype combinations, such as CFH and omega-3 fatty acids.
Strengths of this study include a larger database, with long follow-up. Weaknesses include the fact that this is a post hoc study and it did not look at other known risk factors for AMD, such as BMI or physical activity, to ensure no bias across cohorts. Lastly, the intake of nutrients was gathered using patient questionaries, which may have some inherent errors.
Nonetheless, the conclusion that higher dietary intake of certain nutrients is associated with decreased progression to late AMD is an important message and should be shared with patients with AMD. Further, it suggests that genetic testing may be advantageous in at least certain subsets of our patients.
Perspective
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AREDS and AREDS2 are “gifts that keep on giving,” with many valuable insights still being teased out of the large datasets obtained. The most recent publication, which is a post hoc analysis of the AREDS and AREDS2 cohorts, reaffirms previous research findings that suggest increased dietary intake of certain nutrients is protective against progression to late AMD. Interestingly, this study suggests that the beneficial effects of increasing dietary consumption of specific nutrients may be different and complementary to those achieved by supplementation. For example, the AREDS studies found stronger protective associations with supplementation against neovascular AMD development, while the current study found that dietary intake was more protective against geographic atrophy (GA). Because there are no treatment options to reverse vision loss attributable to GA, prevention is of the upmost importance.
A potential limitation of the study is that dietary consumption of various nutrients was determined using subjective participant reports to “food frequency questionnaires” that asked how often participants consumed each food type (ie, eggs, tuna, etc.) during the preceding year. Questionnaires were completed only once upon enrollment, making it difficult to know whether participants maintained similar dietary habits thereafter.
Diet is one of the few modifiable AMD risk factors, and this study underscores the importance of counseling patients on diet modification to include increased consumption of foods rich in lutein/zeaxanthin, folate, beta-carotene, copper, magnesium, omega-3 long-chain polyunsaturated fatty acids, vitamins A, C and B6, while reducing intake of saturated and monosaturated fats.
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