The old joke, "Your eyesight isn't getting bad; your arms are getting shorter," doesn't seem quite as humorous to the millions of baby boomers who find themselves buying their first pair of reading glasses or, even worse, bifocals.
Although vision deterioration is inevitable with age—"I always tell people if you live long enough, you'll get cataracts," says Dr. Christine Gerbstadt, a spokeswoman for the American Dietetic Association—certain foods can improve eye health. There are plenty of scientific studies establishing the role of carotenoids, vitamins and minerals in reducing vision problems. The most effective nutrients include:
Lutein. This carotenoid can help slow premature and regular aging of the eyes. According to an April 2004 study in Toxicology Letters, lutein is deposited in the lens and the macula lutea, an area of the retina responsible for central and high-acuity vision. The authors conclude that "human intervention studies show that lutein supplementation results in increased macular pigment and improved vision in patients with AMD [age-related macular degeneration] and other ocular diseases."
Lutein is found in leafy green vegetables, including spinach, kale, mustard, collard and turnip greens. It's also in yellow and orange fruits and vegetables, such as oranges, squash, peppers and corn. In addition, look for it in kiwis, broccoli, brussels sprouts, peas and egg yolks.
There are no federal recommended dietary levels for lutein, but Gerbstadt says studies show people should consume around 6 milligrams a day. That's only a half-cup of cooked spinach or other leafy greens, but one and a half cups of orange peppers, 3 cups of broccoli or a whopping 6 cups of corn.
Zeaxanthin. A carotenoid like lutein, zeaxanthin also helps reduce age-related eye issues. A group of Hong Kong scientists published a study in the January 2005 British Journal of Nutrition that reported that wolfberries, which are rich in zeaxanthin, can help prevent AMD.
Zeaxanthin is found in the same foods that contain lutein, but in smaller quantities. Gerbstadt recommends 10 milligrams of zeaxanthin a day for macular degeneration and cataract treatment, and 3 milligrams a day for prevention. But the richest zeaxanthin source—leafy greens—only contains a half milligram per cup. "It's probably pretty hard to get the levels of zeaxanthin you need from food," Gerbstadt says, "but if you're in the ballpark with your lutein, you're going to be close enough on your zeaxanthin. A serving of leafy greens a day basically covers all the bases."
A British study published in the January issue of Nutrition & Metabolism found that participants who ate three eggs a day for 30 days showed improvement in their blood levels of lutein and zeaxanthin. But, "there's no real advantage to eating eggs over fruits and vegetables," Gerbstadt says.
Foods fortified with lutein and zeaxanthin loom on the horizon but aren't commercially available yet. According to the January issue of Functional Foods & Nutraceuticals, "Kemin Foods, the market leader in lutein, has secured a place for its ingredient in more than 1,000 dietary supplements, yet in the last three years has only been able to get lutein into but a handful of beverage brands."
Vitamins E and B. Gerbstadt says vitamin E consumption can help prevent cataracts, retina problems and blood vessel disorders, while deficiencies in vitamin B are linked to cataracts, light sensitivity and bloodshot, dry and burning eyes. In addition, data from the Nurses' Health Study in Boston, published in the April 2005 issue of Archives of Ophthalmology, found that increasing vitamin E, riboflavin and thiamin intake may reduce the progression of macular degeneration.
Vitamins C and E, zinc and beta-carotene. A Dutch study of 4,000 people age 55 and older, published in the December 2005 Journal of the American Medical Association, found that "a high intake of beta-carotene, vitamins C and E, and zinc was associated with a substantially reduced risk of AMD in elderly persons." A below-median consumption of these antioxidants was linked to a 20 percent increased risk of AMD. The data echoes the findings of the 2001 Age-Related Eye Disease Study that showed supplements containing as much as 13 times the recommended daily allowance of zinc, beta-carotene and vitamins C and E slowed the progression of AMD.
Gerbstadt says the eye-lens fluid contains 10 to 15 times the blood concentration of vitamin C compared with other parts of the body, so maintaining those levels can help fight lens-related disorders such as cataracts and glaucoma.
Vicky Uhland is a freelance writer based in Lafayette, Colo.
Natural Foods Merchandiser volume XXVII/number 3/p. 60, 70