Cataracts (clouding of the lenses of the eyes) are a serious problem throughout the world, accounting for half of the 30 to 50 million cases of blindness. But in the US, age-related macular degeneration (AMD), which gradually limits vision, outranks cataracts as the leading cause of blindness in people over 65. The good news is that research now suggests that nutrition can improve both conditions and help prevent - or at least postpone - these eye disorders.

Responsible for your central vision, the macula is a tiny area in the back of the eye behind the opening in the iris. Light shines through the iris directly onto the macula and its pigment functions as a powerful antioxidant, absorbing light that might otherwise cause damage. Analysis of the macula shows that it contains close to 100 times greater levels of carotenes (caretenoids) than any other body tissue. Moreover, the carotenoids lutein and zeaxanthin occur in much higher levels that any of the other carotenes and, hence, are believed to prevent AMD, cataracts and perhaps other degenerative retinal disorders.

Diet's Role in Eye Disorders
Several studies have shown that individuals who consume high levels of dark green vegetables are less likely to get AMD than people who do not. Vegetables that are dark green contain the highest levels of lutein: spinach, collards, kale, mustard greens, green peppers and to a lesser degree, broccoli, Brussels sprouts and cabbage. Yellow corn and egg yolks contain the most zeaxanthin, which makes up approximately 85 percent of the total carotene content in these foods. Other foods that contain high levels of these two carotenoids - between 40 and 50 percent of total carotenoids - are kiwi fruit, grapes, orange juice, zucchini and other kinds of squash.

Years of exposure to sunlight and low levels of antioxidants - particularly carotenoids and vitamins C and E - may contribute significantly to the occurrence of cataracts. Researchers at the Tufts University Human Nutrition Research Center on Aging compared blood serum levels of carotenoids in seventy-seven patients with cataracts against the levels of thirty-five cataract-free people who served as controls. Those who ate fewer than three servings of fruits and vegetables per day had the lowest levels of carotenoids and vitamins and the highest incidence of cataracts.

Low fat diets reduce the amount of carotenoids that can be absorbed from fruits and vegetables since these carotenoids depend on dietary fat for absorption. While foods rich in carotenoids are usually also rich in nutrients for the eyes, you may want to consider extra dietary supplements (6 mg/day) of lutein and zeaxanthin in oil-based soft-gel capsules.

An Antioxidant from the Sea
Shore birds and some species of fish contain high levels of another carotenoid called astaxanthin. Blue light that occurs near the surface of the water is particularly damaging to of the lipids (fatty acids) in the photoreceptors of the eye, causing oxidative damage to the lipid membranes. When these membranes are damaged, vision is impaired and blindness can result. The most efficient free-scavenger of all the carotenoids, astaxanthin absorbs blue light. The bright red pigment of astaxanthin may be seen in some of these species as red or pink flesh (salmon, trout, shellfish) and feathers (flamingos). In some of these species, astaxanthin has been shown to have a vitamin-like quality and may be important for growth as well as antioxidant protection.

Supplement Protection
Vitamin C is the most important water-soluble antioxidant, capable of eliminating free radicals that have been trapped by the lipid-soluble antioxidants, thus completing the cycle of neutralizing free-radical damage. A recent Tufts University study has shown that Vitamin C supplementation (400 to 800 mg/day) for more than 10 years resulted in a 77 reduction in early cataract and an 83 percent reduction in moderate lens opacities among elderly women.In addition, In addition, vitamin C is required for strengthening the capillaries of the retina. OPCs (oligomeric proanthocyanidins) are vitamin C co-factors that occur widely in the skins and seeds of fruit such as grapes. French scientists showed that OPCs can reduce light induced damage (i.e. computer glare) to the retina and may reverse capillary fragility in diabetic retinopathy. A cousin of OPCs, quercetin adds another element of protection for eyes in that it blocks the enzyme aldose reductase which makes sugars harmful to the lens of the eye. Quercetin, OPCs and vitamin C all help reduce allergic irritation to the eyes. All of these vitamin C factors are found in fruits and dark green vegetables.

The herb bilberry (Vaccinium myrtillus) belongs to a family that comprises nearly 200 species of berries including cranberry, cowberry, and blueberry. Bilberries are similar In appearance to blueberries except that the interior of blueberries is golden while that of bilberries is purple. Bilberries are a rich source of anthocyanidins members of the large bioflavonoid family.

They have been popular in Europe for centuries as a treatment for scurvy, infections and eye disorders. While possessing many of the same effects as OPCs including improved blood flow and nutrient delivery to the retina, bilberries have the added benefit of improving the oxygen carrying capacity of red blood cells. Two well designed human studies have shown that bilberries can stop the progression of cataract and reduce capillary permeability in various types of retinopathies. In the U.S., bilberry is available as a dietary supplement but is not commonly available as a food.

DHA and Your Eyes.
The photoreceptors of the eye consist of layers of membranes that interact with light. An integral part of the photoreceptor membranes is the long-chain polyunsaturated fatty acid docosahexaenoic acid or DHA. Bleaching and restoration of the vitamin A containing molecule rhodopsin or visual purple is what allows us to see. DHA forms the structure within which rhodopsin functions and is thus an integral part of vision. Low birth weight infants are at greatest risk for DHA induced vision problems. That's because premature infants are deprived of adequate DHA unless fed breast milk, which contains high levels of DHA. Even full term newborns are not able to synthesize DHA and are dependent on mother's milk to supply it. Formula enriched with DHA would be an acceptable alternative. Fortunately the US Food and Drug Administration recently approved the addition of DHA to infant formule, which will be available in this country before the end of the year.

Dyslexia has been strongly associated with low DHA levels. Some time ago researchers noted that children with this disorder also showed signs of fatty acid deficiencies such as dry skin and hair, frequency of thirst and need to urinate. Sunlight was unusually bothersome and they had difficulty with night vision as well. Dr. Dennis Hoffman and colleagues at the Retina Foundation in Dallas Texas found that some patients with retinitis pigmentosa, a disorder that results in blindness early in life, had abnormal fatty acid metabolism and consequently were low in DHA.

Animal studies have confirmed that DHA is essential for normal vision and that depriving animals of this fat or its precursors results in a variety of vision problems, most of which are corrected with subsequent DHA supplementation. Dietary sources of DHA include fish such as salmon, trout, herring, tuna and anchovies. Supplements of DHA are either derived from algae or fish body oils. Fish liver oils are not a good source of DHA since taking several capsules a day may deliver too much of the fat-soluble vitamins A and D along with the DHA.

Other Supplements for Eye Health
Concentrated in the photoreceptor cells of the retina, Taurine is the major free amino acid found in many tissues of the body, but is. Exposure to light causes a release of taurine from retinal cells. Normally, taurine is synthesized within the body from sulfur amino acids such as methionine and cysteine. According to Dr. Robert Abel, author of "The Eye Care Revolution", the B-vitamin pantothenic acid slows the clumping of lens proteins helping to prevent cataracts. Dr. Abel also recommends increasing the intake of sulfur rich antioxidants such as lipoic acid, glutathione, cysteine and MSM (methylsulfonylmethane). These sulfur containing antioxidants play key roles in scavenging free radicals and preventing damage to eye tissues. It is particularly important to supplement these antioxidants if you have heavy exposure to sunlight either because of where you live or by spending a lot of time outdoors. These antioxidants are rapidly consumed by sunlight and also by smoking cigarettes. Garlic, onions and cruciferous vegetables are good sources of sulfur compounds

Several minerals are also important in antioxidant activity. Zinc is required for well over 300 enzymatic reactions. The most notable of these are zinc/copper superoxide dismutase (SOD) and zinc metallothionein (MSH). SOD is the fifth most plentiful protein in the body and one of the most important free radical scavengers because it breaks down the superoxide radical that's formed as a by-product of normal metabolism. Zinc also stabilizes membrane fatty acids and preserves nerve transmission in the retina as well as the brain and other nerves in the body. MSH is a powerful antioxidant that protects DNA from hydroxyl radical attack. It also detoxifies toxic metals such as cadmium, mercury and lead. Copper and manganese also are needed for SOD enzyme formation and essential for efficient antioxidant function. Selenium is another trace mineral that is a component of an important detoxifying enzyme - in this case, glutathione peroxidase. Peroxides are anther highly reactive form of oxygen free radicals that are particularly damaging to the eye. Generally, these minerals are available in a good multi-vitamin and mineral formula. You will also find them in most formulas for eye health. §

Selected Sources ♦ "The Eye Care Revolution" by Robert Abel (Kensington Books, 1999 $16.00)  ♦ "Carotenoid Nutrition and the Human Retina" by John Landrum and Richard Bone (International Journal of Integrative Medicine May/June 2000)  ♦ "Diet Might Help Prevent Cataracts" (Tufts University Health & Nutrition Letter, Dec. 1999)  ♦ "Lutein and Zeaxanthin Concentrations in Plasma After Dietary Supplementation with Egg Yolk" By GJ Hadleman et al., (Amer. Journal Of Clin Nutr Aug., 1999)  ♦ "Dietary Carotenoids, Vitamins A, C, and E, and Advanced Age-Related Macular Degeneration" By Johanna Seddon, et al., (JAMA, 1994)  ♦ "Inhibition of Oxidative Injury of Biological Membranes by Astaxanthin" by Michi Kurashige, et al., (Physiol. Chem. Phys. & Med. NMR, 1999)  ♦ "Retinopathies et OPC" by MM Verin (Bordeaux Medical, 1978)  ♦ "Long-Term Vitamin C Use Cuts Cataract Risk in Older Women" (Doctor's Guide, May 2001)  ♦ "Bilberry (Vaccinium myrtillus)" by Michael Murray (Am J Nat. Med. Jan/Feb, 1997)  ♦ "Red Blood Cell Membrane Phosphatidylethanolamine Fatty Acid Content in Various Forms of Retinitis Pigmentosa." By Ernst Schaefer, et al., (Lipid Res., 1995)  ♦ "Benefit of Docosahexaenoic Acid Supplements to Dark Adaptation in Dyslexics" by Jacqueline Stordy (Lancet, 1995) 

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