All tissues within your eye require adequate nutrients and oxygen from an uninterrupted blood supply to function properly and provide you with clear vision. The macula is the central region of your retina. It is sensitive to free-radical damage and lack of blood. Carotenoids are colorful pigments found in fruits, vegetables and seafood that are powerful antioxidants and offer protection to the small blood vessels that supply the eye. Some carotenoids, such as astaxanthin, are particularly powerful and have a predilection for the macula.
Macular Degeneration
According to the National Eye Institute, about 9 million Americans 40 and older suffer from macular degeneration, which is a gradual loss of vision in the center of the visual field. Macular degeneration does not cause total blindness because peripheral visual fields are not affected, but reading, driving and recognizing faces eventually becomes impossible. Macular damage is often a result of reduced blood flow because the small arteries that supply the retina are susceptible to blockage, damage and leaking. Carotenoids protect the small vessels and macula from damage. In addition to lack of dietary carotenoids, other factors that contribute to macular degeneration include high blood pressure, atherosclerosis, toxic substances and diabetes.
Carotenoids in the Retina
A main type of carotenoid is known as xanthophyll, most of which can pass the blood-brain barrier and be absorbed by the tissues of your retina. The best known xanthophylls are lutein and zeaxanthin, although astaxanthan may be the most powerful. A 2001 report prepared by Dr. D. Bagchi of the Creighton University School of Health Sciences found that as an antioxidant, astaxanthin is 14 times more potent than vitamin E, 54 times more potent that beta-carotene and 65 times more potent than vitamin C in scavenging free radicals. In addition to protecting blood vessels, lutein, zeaxanthin and astaxanthin absorb certain frequencies of UV light and protect the retinal photoreceptor cells from damage. In general, the more carotenoids the macula contains, the better the protection against light damage and resistance to degeneration.
Special Properties of Astaxanthin
In moderate amounts, lutein and zeaxanthin are strong antioxidants, but in high concentrations caused by supplemental mega-dosing, these carotenoids can act as pro-oxidants. According to a 2006 article published in the "Journal of Natural Products," astaxanthin does not exhibit pro-oxidant activity, despite being a powerful antioxidant and may be the safest carotenoid supplement for eye health. Further, astaxanthin's ability to concentrate in the retinal macula makes it a good choice to specifically combat macular degeneration.
Sources
Astaxanthin is the carotenoid responsible for the red color in salmon, lobster, krill, crab, other shell fish and H. pluvialis, which is an algae used to make the supplemental form. According to certified nutritionist Phyllis Balch in "Prescription for Nutritional Healing," Dr. Mark Tso of the University of Illinois was issued a U.S. patent covering the use of astaxanthin in the prevention of macular degeneration, photic injury, ischemic diseases and inflammatory diseases of the eye and central nervous system.
References
- "Professional Guide to Diseases: Ninth Edition"; Springhouse Publishing; 2009
- "Oxygen Free Radical Scavenging Abilities of Vitamins C, E, A-carotene, Pycnogenol, Grape Seed Proanthocyanidin Extract, Astaxanthin and BioAstin In Vitro -- Final Report to Cyanotech Corporation"; Dr. D. Bagchi; Creighton University School of Health; 2001
- "Journal of Natural Products"; Astaxanthin -- A Carotenoid with Potential in Human Health and Nutrition; G. Hussein et al.; April 2006
- "Prescription for Nutritional Healing"; Phyllis Balch; 2010
