Are Antioxidants Nutritional Sunglasses?

Sunlight—with all of its beneficial effects on mood and vitamin D status, which in turn supports absorbtion of nutrients that protect health of bones and other body systems—causes slow and cumulative damage to skin and eyes. A new study associates high lifetime sunlight exposure with age-related macular degeneration in people who do not get adequate amounts of vitamins C, vitamin E, and zeaxanthin, and found that people who do get enough of these antioxidants were protected.

Natural eye protection

The retina, the light-sensitive tissue that lines the back of the eye, and the macula, the highly specialized structure near the center of the retina, rely on antioxidant-dependent mechanisms to protect against damage from sunlight and other sources. Vitamins C and E, the carotenoids zeaxanthin and lutein, and zinc all take part. As we age, these mechanisms for protection and repair become less able to keep up with the accumulating damage.

Looking at combinations of factors

The study, published in the Archives of Ophthalmology, examined the relationship between sunlight exposure, antioxidant status, and macular degeneration in people over 65. Answers to questions about hours spent in outdoor activities during adulthood as well as geographical histories were used to estimate individuals’ lifetime exposures to blue light, which is believed to be the most damaging wavelength of visible light. The researchers used retinal photographs to identify and measure the degree of macular degeneration and blood tests to measure levels of the antioxidant nutrients vitamins C and E, zeaxanthin, lutein, and zinc.

Of the 4,443 people in the study, slightly more than half had some degree of macular degeneration. The combination of high lifetime blue light exposure and low antioxidant status was linked to increased risk of advanced macular degeneration. Having low levels of a single antioxidant did not appear to increase the susceptibility to light damage; however, having low levels of several antioxidants did. The strongest link between high lifetime light exposure and macular degeneration was seen in people with the lowest levels of three antioxidants—vitamin C, vitamin E, and zeaxanthin.

Taking care of aging eyes

Age-related macular degeneration is a common affliction in seniors and the most common cause of vision loss in people over 50 in the US. People with macular degeneration usually notice a gradual loss of central vision. They may also note that straight lines appear wavy or bent, and may have difficulty reading and seeing details.

The study’s authors had some key recommendations for preventing age-related macular degeneration. “Lowering retinal exposure to blue light and ensuring that intake of key antioxidant nutrients is sufficient are the main recommendations from our study,” they said. “We advise reducing ocular exposure when outdoors by wearing broad-brimmed hats and sunglasses, estimated to reduce ocular light exposure by approximately 40% and 70%, respectively.”

In addition, people concerned about macular degeneration should:

• Avoid the midday hours of most intense sunlight, between 11 a.m. and 3 p.m.

• Eat a varied diet with lots of colorful fruits and vegetables to ensure that their bodies are getting enough carotenoids and vitamin C, as well as bioflavonoid antioxidants that might also be protective.

• Eat plenty of vitamin E–rich foods such as liquid oils, nuts and seeds, tomato sauce, and avocado, and foods with zinc such as meat, dairy, fish, whole grains, and (again) nuts and seeds that help round out the diet by providing these important nutrients.

(Arch Ophthalmol 2008;126:1396–403)

Maureen Williams, ND

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