Your Health by Dr. Rallie McAllister

If your mother ever told you that eating carrots would improve your vision, she knew what she was talking about.

A new study published in the Journal of Food Science offers scientific support for the age-old maternal wisdom. Based on the results of their research, University of Georgia scientists concluded that carotenoids, the pigments responsible for the yellow and orange colors of carrots and other plant foods, can enhance visual performance and help prevent age-related eye diseases.

Two carotenoids in particular, known as lutein and zeaxanthin, are primarily responsible for the beneficial effects. These substances have been shown to enhance visual contrast, reduce glare from light absorption and increase the visual range.

The pigments lutein and zeaxanthin aren't found only in brightly colored plants — they also occur in high concentrations in the macula of the human eye. Located at the back of the eyeball, the macula is a small, yellow-colored structure that is responsible for sharp central vision, making it essential for tasks such as reading, face recognition and driving.

The macula also helps protect the eyes from the harmful effects of ultraviolet light and injury caused by free radicals. Over a lifetime of exposure, free radicals from toxins such as cigarette smoke, radiation and air pollution can destroy the cells of the macula, increasing the risk for a condition known as age-related macular degeneration.

Age-related macular degeneration, or AMD for short, is a chronic eye disease marked by progressive deterioration of the macula. In the U.S. and other industrialized nations, the condition is the leading cause of irreversible visual impairment among people ages 65 and older.

In addition to advancing age, risk factors for AMD include having a family history of the disease, cigarette smoking and excessive exposure to sunlight. Women are more likely to develop the disease than men, and people with light-colored eyes tend to have a greater risk than their dark-eyed counterparts.

Symptoms of AMD include blurred or fuzzy vision and the illusion that straight lines, such as sentences on a page, are wavy. People with the condition also may experience the appearance of a dark area or a blind spot in the center of their field of vision, which can make it nearly impossible to read or recognize faces.

For the vast majority of those with vision loss due to advanced AMD, there is no satisfactory treatment or cure.

Fortunately, there may be a way to reduce the risk of developing the disease in the first place.

Scientists believe that the more lutein and zeaxanthin present in the macula, the greater its ability to protect against vision loss associated with AMD. These carotenoid pigments have been shown to protect the macula by absorbing harmful light from the sun's rays.

Because lutein and zeaxanthin are powerful antioxidant substances, they're also capable of neutralizing free radicals before they can cause oxidative damage that contributes to vision loss.

In spite of the fact that these two carotenoids are critical to vision, the human body is incapable of manufacturing them, and they must be obtained from the foods we eat or from nutritional supplements. Several studies show that both the accumulation and the density of the macular pigment in the eye are entirely dependent upon dietary intake of carotenoids.

In other words, people who don't get enough lutein and zeaxanthin from dietary sources are more likely to have a deficiency of the carotenoids in the macular pigment of their eyes. As a result, they're more susceptible to the development of visual impairment and AMD.

When scientists compared the amount of macular pigment present in the eyes of patients with AMD to the eyes of people without the disease, they found that individuals with the lowest levels of carotenoid accumulation in the macula were significantly more likely to suffer from AMD than those with the highest pigment levels.

You can add more lutein and zeaxanthin to your diet, and to your eyes, by eating more carotenoid-rich foods. Carrots are an obvious choice, but recent research has shown that dark green vegetables are also good sources of the protective compounds.

Although the orange and yellow colors of lutein and zeaxanthin are masked by green pigments in kale, spinach and broccoli, these foods are rich in beneficial carotenoids.

Adding more brightly colored plant foods to your plate is a great way to enhance the visual appeal of any meal. Even better, it might help preserve your ability to appreciate it.

Rallie McAllister, M.D. is a family physician, speaker, and co-founder of www.MommyMDGuides.com, a website featuring child-raising tips from trusted doctors who are also moms. To find out more about Rallie McAllister, M.D., and read features by other Creators Syndicate writers and cartoonists, visit the Creators Syndicate Web page at www.creators.com. COPYRIGHT 2009 CREATORS.COM