Nutrients may prevent blinding disease.

There's no guarantee of attaining Popeye's strength, but a diet rich in spinach and other vegetables can help prevent chronic diseases and keep the pounds off. A new study now shows that spinach and other green leafy vegetables may also help ward off an eye disease that ranks as the leading cause of irreversible blindness in people age 65 and older.

In this disorder, called age-related macular degeneration, the macula -- the part of the retina at the back of the eye -- becomes progressively damaged. As time goes on, victims lose all central vision. Physicians have no cure and no way to prevent it.

Researchers had speculated that certain nutrients in foods, particularly pigment molecules known as carotenoids, might protect against or slow the march of macular degeneration. Johanna M. Seddon of the Massachusetts Eye and Ear Infirmary in Boston and her colleagues decided to test that theory.

The team started its investigation with 356 men and women, age 55 to 80, already diagnosed with advanced macular degeneration. A control group of 520 men and women in the same age range suffered from some other form of eye disease. The researchers questioned the volunteers extensively about their diet. From that survey, the team calculated the amount of specific nutrients and vitamins that each recruit regularly consumed.

The scientists found that people getting the heftiest dose of carotenoids in their diet had a 43 percent lower risk of advanced macular degeneration than people ingesting the least carotenoids.

"The findings are pretty exciting," comments Susan E. Hankinson of Brigham and Women's Hospital in Boston. She calls that risk reduction "quite substantial." Both the study and an accompanying editorial by Hankinson appear in the Nov. 9 JOURNAL OF THE AMERICAN MEDICAL ASSOCIATION.

The carotenoids -- a family of yellow, orange, and red pigments -- are found in fruits and vegetables. Beta-carotene, the best known of the group, has been associated with a lower risk of cancer and heart disease.

However, when Seddon and her colleagues zeroed in on the specific carotenoids protecting the macula, they got a surprise: Beta-carotene wasn't the star of this story. Two other pigments, lutein and zeaxanthin, accounted for the risk reduction.

The beauty of that finding is that it makes biological sense, Hankinson says. Lutein and zeaxanthin form the yellow pigment in the macula of the eye. Researchers believe they may prevent damage to the eye by filtering out visible blue light.

In a related report in the same issue of the journal, another research team studied the relationship between concentrations of all carotenoids in the blood and the risk of heart disease. Dexter L. Morris of the University of North Carolina School of Medicine in Chapel Hill and his colleagues found that people with very high concentrations of carotenoids had a decreased risk of heart disease.

Both studies underscore the fact that researchers still must sort out the complex interplay between certain nutrients and a given health benefit. While other reports have suggested that carotenoids offer some heart protection, this is the first study to peg lutein and zeaxanthin as a shield against macular degeneration.

"It is important to recognize that these findings aren't conclusive," Hankinson says. "We really need additional confirmatory studies."

The jury remains out on whether multivitamin supplements protect against age-related diseases. However, Hankinson and other scientists do advise people to consumer a diet rich in fresh fruits and vegetables. For those who want to boost their intake of lutein and zeaxanthin, spinach and collard greens contain lots of these carotenoids, Hankinson notes.