The photoreceptors that make-up your retina are susceptible to the damaging effects of sunlight. In particular, the sun’s visible light spectrum that consists of the blue wavelength is very damaging, resulting in the degeneration of the retina.
By absorbing blue light, carotenoids protect delicate photoreceptor cells in the retina’s macula from light damage. The retina, especially the dense area called the macula, is composed of the carotenoids lutein, zeaxanthin, and meso-zeaxanthin – pigments that are essential to proper vision. These carotenoids are also called retinal pigments and act as antioxidants and protect the macula from damage by photo-initiated oxidative stress 1,2 Unfortunately, their concentration declines naturally over time, along with a decrease in the conversion of lutein into zeaxanthin and meso-zeaxanthin – an important conversion for maintaining optimal vision. Sources of Retinal Pigments Zeaxanthin and lutein belong to a class of carotenoids known as xanthophylls, which are found in variously hued fruits and vegetables, predominantly in those colored yellow, orange, and green. Xanthophylls serve as natural sunscreens in plants and in your eyes, protecting them from the damaging effects of excessive light-derived energy. Rich food sources of zeaxanthin include orange peppers, sweet yellow corn, honeydew, mangoes, oranges, and peaches. Lutein is found in dark green leafy vegetables, broccoli, asparagus, sweet yellow corn, squash, kiwi, pumpkin, and peas.3 Egg yolks are also loaded with zeaxanthin and lutein, probably even more so than fruits and vegetables. Some scientists now believe that eating an egg a day may help confer some of the beneficial effects of these carotenoids, while not adversely affecting serum cholesterol.3 By the way, lutein is far more prevalent than zeaxanthin in our bodies and our diet, though zeaxanthin appears to be a more chemically potent antioxidant for protecting your retina. Low Levels of Retinal Pigments Cause Disease Scientists believe the retinal pigments are conditionally essential nutrients—that is, nutrients that, when present in optimal amounts, may offer important disease-preventive effects. For instance, long-term depletion of zeaxanthin and lutein is not only associated with eye diseases, but also aging skin, atherosclerosis and bladder cancer.4-6 Scientists have repeatedly demonstrated the protective effects of zeaxanthin, lutein, and meso-zeaxanthin on the eyes. High concentrations of these carotenoids are found in the macula, a specialized area of the eye’s retina that is responsible for detailed vision due to its high concentration of light-detecting cone cells. These carotenoids protect the retina by absorbing harmful ultraviolet rays and blue-green light, which can eventually damage the retina and lead to vision loss.7, thus they can be thought of as natural sunscreens for the eyes. Retinal Pigments as an Eye Sunscreen Once lost, photoreceptors cannot be restored, leading to degeneration of the retina, deleterious accumulation of metabolic debris, and a resultant loss of vision. However, research has shown that maintaining optimal vision is now possible with nutritional supplementation, diet and other lifestyle changes.8 So here’s what I suggest: • Eat lots of lutein- and zeaxanthin-containing vegetables (yellow, orange and green colors). This will go a long way in maintaining the structural integrity of the macula. • Supplement with all three retinal pigments: Lutein, zeaxanthin and meso-zeaxanthin. Taking lutein is not enough. Most of us will not convert it into the necessary forms of zeaxanthin. • Where sunglasses to look cool and protect your eyes from the sun’s damaging blue light. 1. Invest Ophthalmol Vis Sci. 2008 Apr;49(4):1679-85. 2. J Med Liban. 2009 Oct-Dec;57(4):261-7. 3. Br J Ophthalmol. 1998 Aug;82(8):907-10. 4. Med Hypotheses. 2003 Oct;61(4):465-72. 5. J Urol. 2006 Sep;176(3):1192-7. 6. Arterioscler Thromb Vasc Biol. 2004 Feb;24(2):313-9. 7. J Am Coll Nutr. 2000 Oct;19(5 Suppl):522S-7S. 8. J Am Optom Assoc. 1999 Jan;70(1):39-47.