Introduction

One of carrots' claims to fame is their ability to benefit eyesight. Some of this benefit is likely due to carotenoids, the pigments that give the vegetable its characteristic orange color. Scientists are studying the disease-fighting potential of two specific carotenoids, lutein and zeaxanthin; both may play a role in reducing the risk of two degenerative eye diseases, cataracts and age-related macular degeneration (AMD). Researchers from Tufts University, in Boston, recently summarized what scientists now know of the role of carotenoids in eye health.

Poor vision interferes with lifestyle as one ages

More than half of all Americans over age 65 have cataracts, a cloudiness on the lens of the eye that gradually interferes with normal vision. Age-related macular degeneration (AMD), also a leading cause of visual impairment in seniors, does not usually cause blindness, but does make it difficult to read, drive, or engage in other activities that require good central vision.

An ounce of prevention

Scientists have determined that the carotenoids lutein and zeaxanthin accumulate in the eyes, specifically in the lens and the macula (the area on the retina responsible for distinguishing fine details). This led them to speculate that people who consume a diet rich in these carotenoids may be less likely to develop cataracts or macular degeneration. Two recent studies found that eating one-half cup of dark green, leafy vegetables, the most concentrated source of lutein, at least several times each week offered a modest protection against cataracts. Research on the relationship between these carotenoids and AMD is more speculative at this point.

Lifelong exposure to ultraviolet light from the sun may be a key factor the development of age-related eye damage. Aspirin use, smoking, chronic diarrhea, and dehydration have also been implicated. All can cause oxidation, or cell damage, that may harden the eye lens. Antioxidants, like lutein and zeaxanthin, are capable of preventing and maybe even reversing oxidation in the cells of the eye.

An ounce of prevention

The National Eye Institute cautions against relying on lutein supplements for eye health, since there is not enough evidence indicating their effectiveness. Indeed, this summary article looked only at studies involving the intake of carotenoids in foods. While scientists continue to study this issue, there are some things that people of all ages can do to safeguard their eyes: avoid midday sun, wear sunglasses and a brimmed hat while in the sun, and don't smoke. Also, don't wait for definitive eye research to start eating dark green, leafy vegetables like kale, spinach, and collards. It is already well established that these and other colorful vegetables provide vitamins, minerals, and fiber that are beneficial for general health.