Eye-friendly Nutrition: Antioxidants, Carotenoids and Omega-3 Fats
ByCarolineBreton, B.Sc., PDt, Registered Dietitian
Research and innovation in the field of nutrition have generated greater awareness of the role nutrition plays in eye health. According to numerous observational studies1,3, people with dietary intakes high in various carotenoids, antioxidants and omega-3 fatty acids have a lower risk of developing age-related macular degeneration (AMD).
A systematic review published in January 2012 by the U.S. Department of Veterans Affairs discussed the role of nutritional supplements for AMD2. The report aimed to address two key questions: first, in patients with AMD did nutritional supplements containing carotenoids, antioxidants, or omega-3 fatty acids alone or in combination prevent functional visual loss? Secondly, what harm might supplementation with carotenoids, antioxidants and omega-3 fatty acids cause in the adult population?
According to the authors, the evidence of benefit from supplementation with carotenoids and antioxidants on functional vision loss in patients with AMD was based primarily on the results of one large clinical trial and the observed benefit occurred only among patients with category 3 or 4 AMD. One report finding was that carotenoid and antioxidant supplements significantly decrease visual loss and can be recommended for patients with category 3 or 4 AMD. The report identified seven randomized clinical trials of nutritional supplements in AMD patients but significant effects in preventing vision loss were only found in the largest two trials, with the weight of evidence dominated by the Age-Related Disease Study (AREDS) because of its large sample size (N=3640) and the long-term duration of the study (seven years).
The other studies had smaller samples sizes and shorter durations, which may not have been enough to detect a treatment effect. In the AREDS study, the beneficial effect was seen in a combination of antioxidants (500 mg vitamin C, 400 IU vitamin E, and 15 mg beta-carotene) plus zinc (80 mg zinc oxide and 2 mg cupric oxide), but only in the group with category 3 or 4 AMD. Current literature does not support the use of these supplements for patients with mild AMD.
The Department of Veterans Affairs report also discussed the potential dangers of these supplements. Caution is warranted before recommending them to high-risk individuals as certain nutritional supplements have significant potential harms. Vitamin E supplementation is associated with increased mortality and congestive heart failure in high-risk patients, as well as increased risk of prostate cancer, and beta-carotene is associated with increased risk of lung cancer among smokers.
Research on the subject is ongoing. Another very large trail, the AREDS II study, with approximately 4,200 subjects with categories 3 to 4 AMD, is currently underway; it will evaluate the effects of carotenoids (lutein and zeaxanthin) and omega-3 fatty acids (DHA &EPA) on AMD progression.
With an aging baby boomer population and AMD on the rise, it is important to encourage healthy lifestyle choices that may reduce the risks for AMD, as well as other diseases that can affect vision. These choices include:
- Maintaining a healthy weight
- Having an active lifestyle
- Quitting smoking
- Avoiding excessive exposure to sunlight
- Eating a balanced low-fat diet, which includes vitamins C and E, zinc, carotenoids (zeaxanthin, lutein, beta-carotene) and omega-3 fats
- Discussing nutritional supplements with a healthcare provider
The table below summarizes eye-friendly nutrients and food sources.
| Antioxidants | Food Sources |
| Vitamin C:
Also called ascorbic acid, vitamin C is a water-soluble vitamin found in all body fluids. It is mainly found in the fruits and vegetables food group. |
Sources include citrus fruits (oranges, grapefruit and lemons), berries, green leafy vegetables and tomatoes |
| Vitamin E:
A fat-soluble vitamin that can be stored in the liver. It is a very efficient, natural antioxidant. |
Found in vegetable oils, margarines, whole grains, eggs, liver, beans, and green leafy vegetables. |
| Zinc:
An essential element, generally considered non-toxic. Found in a wide variety of food groups, such as meat, milk products and grains. |
Red meat, liver, oysters, beans, chickpeas, whole grains and poultry are rich sources. Also milk products, eggs, fish and nuts. |
| Carotenoids | Food Sources |
| Beta-carotene:
Carotene is one of several kinds of the carotenoid family. Found mainly in plants, carotenoids are commonly bright yellow, orange and red pigments, which give foods their colour. |
Rich sources include carrots, sweet potatoes, squash, cantaloupe, peaches, broccoli and kale. |
| Lutein and zeaxanthin:
These two carotenoids are present in the macula segment of the retina and are believed to play a role in eye health by improving macular pigment density. |
The best food sources of lutein and zeaxanthin include kale, spinach, sweet potatoes, squashes, carrots, cantaloupe, corn, egg yolks and eggs enriched with lutein. |
| Omega-3 fats | Food Sources |
| Alpha-linolenic acid (ALA), Eicosapentaenoic acid (EPA) and Docosahexaenoic acid (DHA). All of these omega-3 fats are important because each has specific health benefits. DHA supports the normal development of the brain, eyes and nerves. | EPA and DHA come mostly from fish and marine sources, plus omega-3 enhanced foods. Sources include Atlantic salmon, rainbow trout, herring, sockeye salmon, white tuna canned in water and omega-3 enhanced eggs. |
References:
1.www.pennutrition.com/KnowledgePathway.aspx
