By Rachel Johnson, Ph.D, M.P.H., R.D., March/April 2009
When I was 7, I longed for bright blue eyeglasses with wings like the ones my neighbor Sue wore. (She was 9, and ultra-cool.) Much to my disappointment at the time, my vision was perfect. With age, that’s changed: When I hit my forties I reluctantly purchased drugstore reading glasses. Now I need bifocals. Frankly, I’m lucky that, so far, that’s all I’ve had to deal with: more than 8 million Americans—including people I know—are facing a vision problem that can’t be corrected so easily: age-related macular degeneration (AMD).
AMD begins when the macula—the center of the retina, and the part of the eye that allows you to see fine detail—starts to break down. This causes cloudy “blind spots” in the center of your vision, which, over time, grow in number and in size, making it difficult to read, drive a car or even recognize faces. AMD is a leading cause of blindness in people over age 60.
Getting older is, in fact, the biggest risk factor for developing AMD; one study found that while the disease is relatively rare in middle age, risk jumps to around 30 percent by age 75. Being female, white or having a family history of AMD also boosts your risk. While some people seem to develop the condition no matter what they do, there are a few lifestyle choices that may help to protect against the disease. For example, smoking appears to increase risk fivefold, so quitting, if you’re a smoker, may reduce your risk. Wearing sunglasses can also help, as light rays from the sun can penetrate the retina and damage its cells—which may explain why a study published last fall found that people who live in sunny areas are more susceptible to AMD. But I’m most interested in the emerging research that suggests eating a nutrient-rich diet may help to prevent the development, or delay the progression, of AMD.
While the signs of AMD may not show up until late in life, much of the damage occurs decades earlier. So what can I eat today to protect my eyes? I did some digging into the research, and here’s what I found. Five foods to help you see more clearly.
Studies show that people with low levels of antioxidants are more likely to develop AMD than those with higher levels. Antioxidants that seem to be especially protective against the disease include vitamin C (in citrus fruits, kiwi and broccoli), vitamin E (in vegetable oils, nuts and avocados) and lutein and zeaxanthin—nutrients that abound in dark leafy greens, such as spinach, kale and collards. While it’s not completely clear how these antioxidants protect your eyes, it seems that they accumulate in the retina where they can mop up free radicals, compounds that damage cells by starving them of oxygen. Lutein and zeaxanthin may also act like natural sunglasses, helping to form macular pigment that filters out some of the sun’s damaging rays.
Egg yolks are also rich in lutein and zeaxanthin, but many of us avoid eggs because we’re worried about their cholesterol content. Research led by Thomas Wilson, Ph.D., associate professor with the Center for Health and Disease Research at the University of Massachusetts-Lowell, suggests that we shouldn’t be so concerned. He found that when people ate eggs regularly—as many as two daily—they significantly increased the levels of lutein and zeaxanthin circulating in their bodies without boosting LDL (“bad”) cholesterol levels. Unless your doctor advises otherwise, go ahead and enjoy eggs regularly. (Just don’t go crazy: the American Heart Association still advises limiting cholesterol intake to less than 300 milligrams [mg] daily, and one large egg yolk has about 213 mg.) Take a tip from Dr. Wilson and scramble your eggs with spinach for an even bigger nutrient boost.
A recent analysis of nine studies that included more than 88,000 participants suggested that people who ate at least two servings of fatty fish (such as salmon, sardines, mackerel, herring or trout) per week were about one-third less likely to develop advanced AMD than those who didn’t. Lead scientist Elaine Chong, Ph.D., a research fellow at the Centre for Eye Research at the University of Melbourne, Australia, explains that omega-3 fatty acids—particularly DHA—in fish are key components of the nerve cells in the retina. “DHA is found in much higher concentrations in the retina than in other parts of the body,” she notes, “thus, a deficiency may trigger AMD.” So commit to eating more fatty fish, and don’t stop there: shellfish, such as oysters and crab, provide good amounts of zinc, another nutrient that’s found in the retina and may also help protect against AMD.
Although it’s always best to get nutrients from food first, supplements are showing a lot of promise in combating AMD. Reports from large-scale clinical trials suggest that, in high-dose supplement form, several nutrients may help to reduce the risk of AMD significantly. If you have any AMD risk factors, talk with your eye-care professional about taking an “eye health formula” supplement. The current supplement formula being studied in major research trials includes 10 mg of lutein (the equivalent of about 3 cups of spinach), 2 milligrams of zeaxanthin and 1 gram total of EPA and DHA (approximately what you get in a 3-ounce serving of salmon). Until further research is in, there’s no advantage to exceeding those amounts. Remember to take it only under medical supervision; even though these supplements are available over the counter, taking megadoses of any nutrient should always be approached cautiously.
People with high blood pressure are more likely to develop AMD, according to the American Academy of Ophthalmology. The theory is that increased pressure damages blood vessels. This hinders blood flow to the eyes, making it harder for protective nutrients to reach the retina and for damaging free-radical debris to be carried away. Losing extra pounds if you’re overweight or obese might also help. Body fat is a major storage depot for fat-soluble nutrients, and excess fat tissue can act as a “sink” for some eye-protective nutrients, making them less available to the macula.
So I’m redoubling my efforts to eat better—especially when it comes to my weak spots, leafy greens and fatty fish. Since my doctor and I don’t think I’m at high risk for AMD (thanks to my lack of family history and the cloudy, northern climate I live in), I’m not taking an “eye health” supplement for now—just a multivitamin and a calcium supplement. But I’m keeping an open mind about the future, while closely watching for new findings on nutrition and eye health. And I’m doing it all wearing fabulous frames that even Sue would envy.
Rachel K. Johnson, EatingWell’s senior nutrition advisor, is a professor of nutrition at the University of Vermont.