To date, the evaluation of a single nutrient in the prevention of age-related eye diseases has not been entirely consistent. The inconsistencies among studies in terms of which nutrients and the amount of nutrients required for protection make it difficult to make specific recommendations for dietary intakes. It is likely that nutrients are acting synergistically to provide protection. Therefore, it may be more practical to recommend food choices rich in vitamins C and E, β-carotene, zinc, lutein and zeaxanthin, and omega-3 fatty acids. Such a recommendation may also provide benefit from possible other components in food that may be important. Therefore, an awareness of dietary sources of key nutrients important for ocular health is important for both the patient and health-care provider. Good sources of vitamin C include citrus fruit, berries, tomatoes, and broccoli (). Good sources of vitamin E are vegetable oils, wheat germ, nuts, and legumes (). β-Carotene can be found in carrots, apricots, sweet potatoes, and pumpkins (). Oysters, beef, and other meats are rich sources of zinc. Nuts, legumes, and dairy are relatively good plant sources of zinc (). The two foods that were found to have the highest amounts of lutein and zeaxanthin were kale and spinach (). Other major sources include broccoli, peas, and brussels sprouts. Fish oils are the primary source of omega-3 fatty acids ().
A healthy diet including a variety of fresh fruit and vegetables, legumes, lean meats, dairy, fish, and nuts, will have many benefits and will be a good source of the antioxidant vitamins and minerals implicated in the etiology of age-related eye health. There is no evidence that nutrient-dense diets high in these foods, which provide known and unknown antioxidant components, are harmful. In fact, intake of fruits, vegetables, and legumes is associated with reduced risk of death due to cancer, cardiovascular disease, and all causes.34
Such a dietary recommendation does not appear to be harmful and may have other benefits, despite its unproven efficacy in preventing or slowing age-related eye disease. Furthermore, the hypothesis that antioxidant and anti-inflammatory nutrients may be of benefit in age-related eye health is plausible, given the role of oxidative damage and inflammation in the etiology of age-related eye diseases.
The AREDS1 trial found that supplementation with vitamins C and E, β-carotene, zinc, and copper reduces the risk of developing advanced AMD. Based on the supporting literature, including observations from AREDS1, AREDS2 will evaluate lutein, zeaxanthin, and the omega-3 fatty acids EPA and DHA on reducing the risk of advanced AMD. Although AREDS1 supports a role for these nutrients in AMD, it is reasonable to believe that they are also important for the prevention or treatment of other major age-related eye diseases, given the role of oxidative stress and inflammation in their etiologies.37
In fact, the American Academy of Ophthalmology has developed guidelines for the use of omega-3 fatty acids for potential benefit in dry eye.38
Dietary data from NHANES indicate that the intake of the key ocular nutrients may be inadequate in those ≥50 years of age. This gap may be filled by creating an awareness of these nutrients and their dietary sources. Therefore, an educational tool may be useful to aid in the selection of food/nutrient choices for optimal eye health.