The eyes consist of various delicate tissues and rely on many small blood vessels and nerves to provide healthy vision. As such, the visual system is especially sensitive to harmful free radicals, which are created from oxidation reactions within the body and capable of damaging blood vessels and other tissues. Lutein, other carotenoids, and certain vitamins are powerful antioxidants that protect the eye and prevent degenerative diseases. The National Eye Institute claims that nine million Americans aged 40 and older have macular degeneration and 20 million have developed cataracts.
Antioxidants
Antioxidants are substances capable of inhibiting the oxidation of other substances. Oxidation reactions within the body are essential for healthy human biochemistry, but they can produce harmful free-radicals. Free radicals start chain reactions within cells that lead to deterioration, or aging, and ultimately, death. Free radicals are particularly damaging to the delicate tissues of the eye, such as the macula, and the small arteries that provide oxygen-rich blood, according to "Human Biochemistry and Disease." Antioxidants, such as lutein, beta carotene, and vitamins A, C and E, terminate these chain reactions by removing free-radical intermediates and help to protect the eye from damage.
Lutein
Lutein is a powerful antioxidant classified as a yellow carotenoid, a colorful compound found in vegetables and fruit. High concentrations of lutein congregate within the macula lutea of the eye, which is the central part of the retina responsible for clear vision. Lutein protects the macula from free-radical damage. It also absorbs blue frequencies of light, which protects retinal photoreceptor cells from excessive sunlight damage. A Veterans Hospital study reported in a 2004 edition of "Optometry" noted that lutein supplements significantly improved the vision of older patients with macular degeneration and may contribute to reducing the progression of cataracts.
Beta-Carotene
Beta-carotene is an orange carotenoid found in carrots and sweet potatoes, and also a strong antioxidant. It is not technically a vitamin, but it is considered a precursor in the formation of vitamin A. Vitamin A is also a very active antioxidant and an essential nutrient in the formation and maintenance of the mucous membranes that line the eye. These moist membranes provide protection from pathogens and debris and act as lubrication for the eyelid during blinking. Vitamin A is also needed for the synthesis of rhodopsin, a light-sensitive pigment within the retina essential for night vision.
Vitamin C
Vitamin C is a powerful antioxidant and stimulator of the immune system. It is also needed for tissue repair and to synthesize collagen, which is especially important for the small arteries that feed the eye. According to "Vitamins: Fundamental Aspects in Nutrition and Health," vitamin C has also demonstrated the ability to reduce the progression of cataracts, which is a steady reduction in the opacity of the lens of the eye leading to blindness.
Vitamin E
Vitamin E is another strong antioxidant that is also helpful in reducing the clotting properties of blood platelet cells, which is important in maintaining a steady blood supply to the oxygen-hungry tissues of the eye. Vitamin E is associated with potentially reducing the risk of certain eye diseases, such as macular degeneration and cataract formation, but the scientific studies are mixed and inconclusive, as cited in "Medical Nutrition and Disease."
References
- "Professional Guide to Diseases: Ninth Edition"; Springhouse Publishing; 2009
- "Human Biochemistry and Disease"; Gerald Litwack; 2008
- "Optometry"; Double-Masked, Placebo-Controlled, Randomized Trial of Lutein and Antioxidant Supplementation in the Intervention of Atrophic Age-Related Macula Degeneration: The Veterans LAST Trial (Lutein Antioxidant Supplementation Trial); S. Richer et al.; April 2004
- "Vitamins: Fundamental Aspects in Nutrition and Health"; G. Combs; 2008
- "Medical Nutrition and Disease: A Case-Based Approach"; Lisa Hark; 2008
