To help clinicians guide patients, this article provides a practical overview on three of the most common ocular conditions for which supplements and dietary factors may play a role.
Macular Degeneration – The Age-Related Eye Disease Study (AREDS) and the Age-Related Eye Disease Study 2 (AREDS2) are two of the largest and most rigorous clinical trials that have investigated the effects of nutritional supplementation on the progression dry age-related macular degeneration (AMD) to wet AMD. Observational trial also have assessed the impact of diet and supplements on the development and progression of AMD.
Results - Patients without AMD did not benefit from taking the AREDS formulation. Patients with mild or borderline AMD did not benefit from taking either the AREDS or AREDS2 formulation. Both formulations slightly lowered the risk for AMD progression in those patients with intermediate or advanced AMD. Patient who smoke should take the AREDS2 formulation to avoid the beta-carotene in the AREDS formulation, which can increase the risk for lung cancer. Lutein, zeaxanthin, and omega-3 fatty acids were included in the AREDS2 formulation but did not decrease the risk for AMD progression. The Blue Mountains Eye Study found that the consumption of vegetables and dietary lutein and zeaxanthin was associated with a reduced risk for AMD. Patients with intermediate or advanced AMD should be encouraged to take the AREDS or AREDS2 formulation as a nutritional supplement. Smoking is a risk factor for the development and progression of AMD and should be discouraged. Physical activity should be encouraged, as it has been demonstrated to have a modest protective effect. A diet consisting of fish, fruits, leafy greens, and nuts has been shown to be beneficial in some studies.
Cataracts – AREDS also addressed the benefits of antioxidants on cataracts as did the cross-sectional Blue Mountains Eye Study, Physicians’ Health Study and Beaver Dam Eye Study.
Results – Lutein, zeaxanthin, and B vitamins may decrease the risk for cataracts. Large, randomized trials found no benefit to taking vitamins C and E, beta-carotene, or selenium. The results are mixed regarding the potential benefit of a multivitamin. Sunlight exposure likely plays a role in the pathogenesis of cataracts, although knowledge of their exact pathogenesis is not fully understood.
Dry Eye Disease – The Tear Film & Ocular Surface Society International Dry Eye Workshop II (TFOS DEWS II) and Dry Eye Assessment and Management Study (DREAM) investigated the effects of supplementation on DED.
Results – Systemic dehydration may contribute to the severity of dry eye as can alteration of environmental factors. In DREAM, omega-3 supplements were no better than the placebo olive oil decreasing the signs and symptoms of dry eye. Antioxidant supplementation has shown some promise in the treatment of dry eye, but the trials have been relatively brief.
I know the data presented above is fairly dry as is often the case in these large studies. I can be more specific about dietary recommendations. Fruits and vegetables that are yellow, red, or orange are the most effective foods for the prevention and treatment of cataracts. They are probably of benefit for AMD and Dry Eye as well. Avoid the use of Gingko biloba in wet macular degeneration.
The omega-3 fatty acids have so many health benefits that I recommend you take them daily in spite of the evidence in these studies. By the way, the use of olive oil (an omega-6 fatty acid) does not constitute a placebo. It provides vital anti-inflammatory prostaglandin 1 compounds for the human body.
If you have eye health issues, consider the AREDS2 formulation. It contains lutein, zeaxanthin, omega-3 fatty acids, and a small amount of zinc. The AREDS formula is vitamin C, vitamin E, beta-carotene and a high dose of zinc with a little copper. However, without a diet high in red, yellow and orange fruits and vegetables, regular exercise and no smoking, the supplementation is of limited value. Finally, drink plenty of clean water daily to avoid dehydration.
Source: October 24, 2018 NIH