Mom was right: eating your carrots really will help your vision. Eating your spinach, collards and kale—especially if you whisk them up in an omelet—is even better for eye health.
Start including certain nutrients in your daily diet, and you can help protect your vision and prevent eye diseases such as cataracts (clouding of the lens) or age-related macular degeneration (progressive deterioration of the retina's center). These two devastating conditions cause impaired vision and blindness for millions of people in the United States and worldwide.
Although these problems appear as we age, the process that leads to them begins many years before. Taking the right nutritional steps may reduce your risk of developing these vision-robbing conditions or help slow their progression if they've already begun.
Seeing the light
Sunlight is great for your garden, but it damages eyes. The amount of lifetime exposure you have to sunlight increases your risk of eye disease.
"Think of a salad in the sunlight. With time, it wilts. The same kind of damage occurs with the eyes," says Elizabeth J. Johnson, PhD, a research scientist and assistant professor at the Tufts University Jean Mayer USDA Human Nutrition Research Center on Aging in Boston.
Destructive light waves directly hit the macula, the central part of the eye's retina. "With time, the macula tends to be the part of the retina that falls apart first," Dr. Johnson says. A yellowish pigment, or color substance, in the macula helps filter this harmful light. It also reduces free radicals, compounds that can break down cells through oxidation.
Antioxidants are natural protectors, helping to prevent oxidative harm throughout your body. A special mixture of antioxidants (vitamins C and E, as well as beta-carotene) and minerals (zinc and copper) has been shown to help people who are at high risk for developing advanced age-related macular degeneration.
The National Eye Institute, which sponsored the antioxidants research known as Age-Related Eye Disease Study (AREDS), recommends that antioxidant formulation for high-risk individuals. That research is now in a second stage, looking at the role of other antioxidants, called carotenoids, and omega-3 fatty acids in preventing eye disease.
You can see carotenoids, literally, because they are plant pigments. They're especially visible in autumn, as tree leaves lose the green (from chlorophyll) in their leaves, and the yellows, reds and oranges from carotenoids are revealed.
Although there are hundreds of carotenoids in nature, the food we eat contains just 50 or so, says Dr. Johnson, who has studied the function of carotenoids in eye health. Our bodies actually take in only 20 of those, including beta-carotene, found in carrots and winter squash, and lycopene, abundant in tomatoes.
Only two carotenoids manage to get their nutritional benefit to the retina's vulnerable macula. These are lutein and zeaxanthin, antioxidants that help build yellow, light-absorbing macular pigment.
Sources of lutein and zeaxanthin
Lutein and zeaxanthin usually occur together in foods. Diets low in these carotenoids increase the risk of age-related macular degeneration. A large group of older women who showed early signs of that disease and consumed higher amounts of lutein and zeaxanthin had slower progression of the disease than those women with lower intakes of the two carotenoids.
You'll find the most lutein and zeaxanthin in dark green leafy vegetables such as spinach, kale, collards and turnip greens. They also occur, to a lesser extent, in broccoli, peas, corn, orange peppers, persimmons and tangerines.
Eggs are an especially good source. Think of the yellow yolk, and you'll know where the lutein is found. (Lutein in manufactured supplements comes from marigold petals.)
Our bodies use the lutein and zeaxanthin found in eggs more readily than that in spinach or even lutein supplements. Dr. Johnson's research showed that this bioavailability is strong, even though the amount of carotenoids in each egg is much less. "We found that lutein in egg is about three times more available than lutein from vegetables," she says.
And forget the bad reputation eggs once had: Eating one egg a day has been shown to increase lutein and zeaxanthin concentrations in a group of adults who were older than 60 without raising cholesterol or triglyceride levels.
"I really believe in eggs," Dr. Johnson says. "They're terrific. I can even get my kids to eat 'em."
Omega-3s show promise
Can increasing your intake of the omega-3 fatty acids help your eye health? These antioxidants, found chiefly in fish, fish oil, flaxseed, walnuts and canola oil, are being studied for their possible role in reducing the risk of many health conditions, including eye diseases.
One of these fatty acids, known as DHA (docosahexaenoic acid), may be linked to the risk of age-related macular degeneration. People who eat diets low in DHA are more at risk of that disease, as well as of dementia and cognitive decline.
Dietary omega-3 may combat another eye problem—glaucoma. Laboratory rats fed a diet with increased omega-3 showed a lessening of intraocular pressure, a factor that could influence glaucoma risk.
More tips for eye health
- You can get the 6 milligrams daily of lutein and zeaxanthin recommended for health benefit by increasing vegetables and fruits in your diet. The average U.S. resident gets only 1.7 milligram each day.
- If you take a lutein supplement, Dr. Johnson suggests taking it with a meal or snack that contains a little fat (such as a glass of low-fat, not skim, milk). Both lutein and zeaxanthin are fat-soluble, so you need to have some fat to aid absorption. This isn't necessary with eggs—the lecithin in them does the trick.
- Different people absorb lutein and zeaxanthin in varying amounts, even when they consume identical portions. Excess body fat may be one reason, Dr. Johnson says, because it stores the lutein and may affect how it's transported through the body.
- The AREDS study identified a formulation of antioxidants and minerals for people at high risk of developing age-related macular degeneration. That mixture includes: 500 mg vitamin C, 400 IU vitamin E, 15 mg beta-carotene, 80 mg zinc and 2 mg copper (needed to prevent anemia caused by high zinc intake). Talk with your doctor before taking any supplements. This mixture does not replace any multivitamin you may be taking. The formula may change once the research phase on lutein, zeaxanthin and omega-3 fatty acids is evaluated.
- When outside, help protect your eyes by wearing sunglasses and a brimmed hat.