Eat five to nine servings of highly colored fruits and vegetables a day and you will be doing your eyes a service.
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Line them up on your kitchen counter–corn, red and yellow peppers, carrots, yellow squash, dried apricots, spinach, kale, red grapes, kiwi fruit, blueberries, green peas, pumpkin, sweet potatoes, oranges, honeydew melon. These highly colored foods are sure to please the eyes as well as tempt the taste buds. Eat five to nine servings of these and other fruits and vegetables as a regular part of your diet, and you’ll be doing a service to your eyes.
Except for corrective lenses, most people don’t even think about the health of their eyes until it’s too late to take preventive action. While rare during young adult life, eye disorders such as cataracts, macular degeneration, glaucoma and diabetic retinopathy become increasingly common with age, sometimes leading to severe limitation of sight or even blindness. About 16 million Americans age 45 and over report some kind of vision loss.
Rather than wait until vision starts to slip away, it’s best to be pro-active–by protecting your eyes from the sun, not smoking, getting regular exercise and eating a nutritious diet.
While most of us don’t think of the eyes as beneficiaries of a nutritious diet, important links have been documented. The eye, like the kidney, is full of tiny blood vessels that can be affected by saturated fats in the diet or, in the case of diabetics, by uncontrolled blood sugar.
Probably the greatest danger comes from exposure to sunlight. If your forehead is showing the signs of sun exposure over a few decades, your eyes have likely experienced a similar deterioration. Ultraviolet rays initiate an oxidation process, creating damaging by-products known as free radicals. Eventually, oxidative damage leads to cataracts and macular degeneration, the two most common causes of age-related visual decline and blindness.
Protecting your eyes by wearing sunglasses is an obvious preventive measure. And research over the past two decades has found that it’s equally important to eat a healthful diet, rich in fruits and vegetables.
Vitamin C Cuts Cataract Risk
A cataract is a clouding of the normally clear lens of the eye. About half of Americans age 75 and over have cataracts that limit their vision enough to require treatment.
A cataract is caused by a breakdown of proteins in the lens, usually developing over a number of years and linked to oxidative stress and the buildup of free radicals. The damage may start with an eye injury, an infection, a disease such as diabetes, the aging process or, most commonly, exposure to ultraviolet light.
Concentrations of vitamin C, a water-soluble antioxidant, are 20 times higher in the eye than anywhere else in the body, and scientists believe that this is to counter the oxidation process and remove damaged proteins from the lens. Vitamin E, a fat-soluble antioxidant, is also present in somewhat high quantities in the lens, and it is believed to have a similar protective effect. Other antioxidants are also believed to play a role.
Women with a vitamin C intake of 352 mg or more a day had a 57% reduced risk of developing a cortical cataract.
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Data from the Nurses’ Health Study found that women with the highest intake of foods rich in vitamin C had a reduced risk of nuclear cataracts, the most common kind.
Another study found that women under age 60 who had a vitamin C intake of 352 milligrams or more had a 57 percent reduced risk of developing a cortical cataract (a type likely to occur among diabetics) compared to subjects who consumed less than 140 milligrams a day.
The RDA for vitamin C is only 75 milligrams (110 for smokers), but a person eating five to nine servings a day of fresh fruits and vegetables, especially citrus fruits and bell peppers, would get several times that amount. Most of the women in the study also took vitamin supplements.
Dark green and deep yellow vegetables, are high in lutein and zeaxanthin, substances that protect against AMD.
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Other substances associated with a decreased risk of cataracts were vitamin E, riboflavin, folate, beta carotene, lutein and zeaxanthin.
Antioxidants Combat AMD
Cataracts can be removed surgically, but age-related macular degeneration is incurable, and it’s the most common cause of vision loss in persons age 55 and over.
AMD involves a breakdown of light-sensitive cells in a central area of the retina known as the macula lutea. It’s the area that gives color vision and allows us to distinguish detail.
The macula is yellow in color, and this pigment is derived from antioxidant plant chemicals lutein and zeaxanthin. These carotenoids are believed to protect the eye by absorbing blue light and neutralizing free radicals that accumulate as a by-product of oxidation.
According to one study, subjects consuming an average of 5.8 milligrams of lutein and zeaxanthin a day had a 57 percent reduced risk of AMD. The average American consumes less than one-third that amount.
Good food sources of lutein and zeaxanthin include kale, collard greens, spinach, turnip greens, broccoli, squash, corn, red and yellow bell peppers, oranges, red grapes and guava juice. Most of these foods are also rich in vitamins C and E. Studies have found that these antioxidant vitamins offer protection against AMD as well as cataracts.
Conducted before lutein and zeaxanthin were available in a form suitable for research, the Age-Related Eye Disease Study (AREDS) published in the Archives of Ophthalmology [October, 2001] concluded that antioxidant plus zinc supplements are a good idea for persons with established AMD. Subjects given 500 milligrams of vitamin C, 400 IU of vitamin E, 15 milligrams of beta-carotene and 80 milligrams of zinc (plus two milligrams of copper to prevent anemia) daily showed a 25 percent reduced risk of progressing to advanced AMD over a seven-year period.
The AREDS authors recommended that all Americans age 55 and over get regular dilated eye examinations to determine their risk of advanced AMD and the possible need for supplementation. Supplements are not without risk, of course, and high doses of vitamins should be taken under a doctor’s supervision.
For most Americans, simply following FDA dietary guidelines is probably sufficient to keep the eyes healthy. At least a third of the recommended five to nine servings of fruits and vegetables a day should be dark green or deep yellow in color. Foods which please the eye may also help feed it.
REFERENCES:
Amber Ackerson, “In Focus: Picture-Perfect Eye Health,” Better Nutrition, September, 2003.
Hannah Bartlett, “AREDS: The Conclusions,” Optician, January 31, 2003.
Rosalie Marion Bliss, “Nutrition & Eye Health,” Agricultural Research, August, 2003.
“Duke Study Shows Need for Nutrition in Confronting eye Diseases,” Angiogenesis Weekly, October 17, 2003.
Georgia E. Hodgkin, “The Eyes Have It...Or Need It,” Vibrant Life, September, 2001.
“Lutein To Help Support Eye Health,” Journal of the American Dietetic Association, August, 2002.
“Nutrients May Prevent Age-Related Eye Diseases,” Health & Medicine Week, November 26, 2001.
“Nutrition and Eye Health,” Nutrition Today, September-October, 2002.
“Supplements Slow the Course of Macular Degeneration,” Harvard Women’s Health Watch, December, 2001.
“Vitamin C and Cataract Risk in Women,” Women’s Health Watch, May, 2002.
