Two carotenoids, lutein (pronounced loo-teen) and zeaxanthin (pronounced zee-uh-zan-thin), are antioxidants that are located in the eye. Green leafy vegetables, as well as other foods such as eggs, contain these important nutrients. Many studies have shown that lutein and zeaxanthin reduce the risk of chronic eye diseases, including AMD and cataracts.
Lutein and zeaxanthin filter harmful high-energy blue wavelengths of light and help protect and maintain healthy cells in the eyes. Of the 600 carotenoids found in nature, only these two are deposited in high quantities in the retina (macula) of the eye.
The crystalline lens (the natural lens in the eye) primarily collects and focuses light on the retina. To do this throughout your life, the lens must remain clear. Oxidation of the lens is a major cause of cataracts, which cloud the lens.
There is a lot of evidence that lutein and zeaxanthin reduce the risk of AMD. In fact, in the Age-Related Eye Disease Studies (AREDS and AREDS2), the National Eye Institute found that taking certain nutritional supplements every day reduces the risk of developing late AMD. Beyond reducing the risk of eye disease, separate studies have shown that lutein and zeaxanthin improve visual performance in AMD patients, cataract patients and people in good health.
Vitamin C (ascorbic acid) is an antioxidant found in fruits and vegetables.
Vitamin C helps promote healthy capillaries, gums, teeth, cartilage and the absorption of iron. Almost all cells of the body depend on it, including those of the eye, where it is concentrated in all tissues. Vitamin C also supports the health of blood vessels in the eye.
Numerous studies have linked vitamin C intake and decreased risk of cataracts. In one study, women taking vitamin C for 10 years or more experienced a 64 percent reduction in the risk of developing nuclear cataracts. Researchers estimate that by delaying the onset of cataracts for 10 years, half of cataract-related surgeries could be averted.
The landmark Age-Related Eye Disease Study (AREDS), sponsored by the National Eye Institute, linked AMD and nutrition. The study showed that people at high risk for the disease who took 500 mg/day of vitamin C, along with beta-carotene, vitamin E and zinc supplementation, slowed the progression of advanced AMD by about 25 percent and visual acuity loss by 19 percent. Other studies have confirmed these results.
Vitamin C is found almost exclusively in fruits and vegetables, including citrus fruits such as oranges, lemons, grapefruit and limes. The table above lists foods known to be high in vitamin C. Also, the USDA Nutrient Database offers comprehensive nutritional information on more than 8,000 raw and prepared foods.
Research has shown that vitamin E, found in nuts, fortified cereals and sweet potatoes, can protect cells of the eyes from damage. This damage is caused by unstable molecules called free radicals, which break down healthy eye tissue. When this happens, the risks for age-related macular degeneration (AMD) and cataract formation increase.
Studies indicate that vitamin E reduces the progression of AMD and cataract formation. Vitamin E also plays a significant role in the immune system, the health of cell membranes, DNA repair and other metabolic processes.
Studies have indicated adding vitamin E to the diet can delay cataract formation. A recent study demonstrated that higher dietary intakes of lutein and zeaxanthin along with vitamin E significantly decreased the risk of cataracts.
The landmark Age-Related Eye Disease Study (or AREDS), sponsored by the National Eye Institute, established that AMD is linked to nutrition. The study showed that a 400 IU/day intake of vitamin E, taken with beta-carotene, vitamin C and zinc supplementation, slows the progression of AMD by about 25 percent in individuals at high risk for the disease. Seven smaller studies have confirmed these results.
Dietary fat is an important source of energy and a necessary part of the human diet. Fatty acids, a component of fat molecules, are important in keeping our eyes healthy.
Zinc is an essential trace mineral, or “helper molecule.” It plays a vital role in bringing vitamin A from the liver to the retina in order to produce melanin, a protective pigment in the eyes. Zinc is highly concentrated in the eye, mostly in the retina and choroid, the vascular tissue layer under the retina.
People at high risk for age-related macular degeneration (AMD), or who are already experiencing the early stages of AMD, may benefit from increased zinc intake. The human body does not produce the zinc it needs, so daily intake of zinc through diet, nutritional supplements, or fortified foods and beverages is important for the maintenance of good eye health. Red meat, seafood, poultry, eggs, wheat germ, mixed nuts, black-eyed peas, tofu and beans contain zinc.
The landmark Age-Related Eye Disease Study (AREDS), sponsored by the National Eye Institute, established that AMD is linked to nutrition. The study showed that individuals at high risk for AMD could slow the progression of advanced AMD by about 25 percent and visual acuity loss by 19 percent by taking 40-80 mg/day of zinc, along with certain antioxidants. Taking higher levels of zinc may interfere with copper absorption, which is why the AREDS study also included a copper supplement.