By Melissa Tennen
You can’t tell what time it is. You can’t read as well as you used to. You can’t even watch television. You may have a progressive condition with no cure called age-related macular degeneration (AMD).
The disease isn’t inevitable, experts say. Eating spinach or other green, leafy foods may help reduce your risk for the disease or slow down its getting worse if you do have it.
Two pigments in these plants do more than just give plant foods color. They can help keep your eyes healthy. Known as lutein and zeaxanthin, these elements protect cells from damaging effects of free radicals, which are byproducts of the normal functions of cells.
Left unchecked, these free radicals damage the highly sensitive retina, possibly leading to AMD.
Because they counteract the damage of free radicals, lutein and zeaxanthin are part of a family called antioxidants. Like other antioxidants, lutein and zeaxanthin are not made in the body and must be ingested through foods such as green, leafy vegetables or supplements.
The macula, the part of the retina at the center back of the eye, allows our eyes to focus on fine details. This is how we can read or see a photograph. AMD is a gradual, painless deterioration of the macula. AMD affects only the macula and leaves peripheral vision intact.
Lutein and zeaxanthin are believed to protect the macula by the combined benefits of quenching oxidative byproducts and neutralizing free radicals caused by cell activity set off by sunlight. People with light-colored eyes are particularly vulnerable.
“This area is at a big risk for a lot of antioxidant activity. So it makes sense that eating foods rich in lutein and zeaxanthin would help prevent this damage,” says Felix M. Barker, O.D., research director and professor of optometry at the Pennsylvania College of Optometry in Elkins Park. The American Optometric Association offers a Web site to help determine your risk for AMD and cataracts by taking you through a questionnaire about your diet and makes recommendations.
Barker encourages his patients to consume foods rich in lutein such as spinach and kale, and in zeaxanthin such as peppers and corn.
How much should you get? Nutritionists use 6 mg a day for lutein as a guide because that’s how much is in one serving of leafy vegetables. In the Harvard study, five servings a week meant people had a 43 percent reduced risk of developing the disease. Most experts say aim for five servings of leafy greens each week. No set amount has been shown for zeaxanthin.
Researchers are still analyzing the antioxidant/AMD connection. In 2001, the Age-Related Eye Disease Study (AREDS), sponsored by the National Eye Institute, proved a high-dose regimen of vitamin C, vitamin E, beta-carotene and zinc lowered the risk of developing more advanced AMD by about 25 percent for those with moderate AMD or advanced disease in one eye. However, for those study participants who had either no AMD or early AMD, the study lasting more than six years did not show that this high-dose therapy offered any benefit.
“After AREDS was started, two Harvard studies were published, one about lutein and another about fats,” says Lylas G. Mogk, M.D., founding director of the Visual Rehabilitation and Research Center of the Henry Ford Health System, chairwoman of the American Academy of Ophthalmology Vision Rehabilitation Committee, and co-author of the book, “Macular Degeneration: The Complete Guide to Saving and Maximizing Your Sight.”
“One of the studies found that people who ate five servings a week or more of dark green leafy vegetables rich in lutein had 43 percent less macular degeneration,” she says. “It doesn’t prove cause and effect, but it has a fairly impressive correlation. It’s enough for me to encourage my patients to take it. It makes sense and all falls into place into what we already know.”
When AREDS started, no one was sure how these antioxidants helped eye health. So researchers did not include them in the study. The same is true for omega-3 and omega-6 fatty acids. However, the other Harvard study showed people with lower rates of macular degeneration ate diets rich in omega-3 fatty acids found in fish, fish oil and flaxseed oil, and consumed less omega-6 acids in the vegetable oils in most packaged and processed foods.
“It’s somewhat analogous to colon cancer,” says Tom Hoglund, spokesman and communications director for the nonprofit Foundation Fighting Blindness. “If you eat enough roughage throughout your life, you may help prevent colon cancer. But once diagnosed, it’s not going to be cured with a high-fiber diet. Similarly, a diet high in antioxidants may help reduce the risk of macular degeneration, but diet won’t cure the disease. Clearly, more effective treatments are needed for macular degeneration.”
Researchers do not know what causes AMD, but some people are more prone to the disease than others. Risk factors include age, smoking, diet, environmental exposures, sensitivity to sun, heredity, gender (women are twice as likely as men), poor diets and race. Fair-skinned people with light-colored eyes are more vulnerable.
AMD is expected to be a health epidemic as baby boomers get older.
“I don’t think AMD, in general, has high awareness. Some people think it’s just a part of getting old,” Hoglund says. “It’s a looming health care crisis.”
About 1.65 million Americans age 50 and older have the more advanced stages of the disease. The nonprofit education group, Prevent Blindness America, estimates more than 13 million Americans age 40 and older show signs of the disease.
“It’s a real quality-of-life issue. You can’t drive. You’re trapped in your house. You can’t sew. You can’t read. The skills you have honed your entire life, you can’t use,” Hoglund says.
However, Mogk says all is not lost if you have the disease.
“People with low vision who get appropriate tools and good training from an occupational therapist specializing in visual rehabilitation or other visual rehabilitation professional can continue to lead full and active lives despite vision loss,” she says.
Aside from antioxidants and nutrients, you also can protect yourself by wearing sunglasses when outside, not smoking and regularly seeing an eye care professional.
“For those who don’t have AMD, prevention is really important since there is no cure and no really effective treatment,” Mogk says. “You should do all that you can do.”