Eating a diet rich in fruits, vegetables and dairy products appears to help maintain your ability to function normally as you age, a new study reports.

Older people who consumed more of these foods had less risk of physical limitations, such as the inability to walk a quarter mile or climb 10 steps, which are often the first signs of disability.

And those who ate the most fruits and vegetables had a lower risk of functional limitations nine years after they were initially evaluated, said study author Denise Houston, a research associate at Wake Forest University.

The results are published in the February issue of the American Journal of Clinical Nutrition.

In their study, Houston and her team initially collected data on 9,404 healthy black and white men and women, 45 to 64 years of age. They were part of the Atherosclerosis Risk in Communities Study.

Nine years later, the researchers looked at the participants' diet and levels of disability. They tested the people's ability to perform 12 daily activities, such as dressing and feeding themselves, being able to cook and manage their money, and being able to walk a quarter mile and walk up 10 steps without resting.

The researchers found that eating more dairy products and fruits and vegetables was associated with a lower risk of functional limitations. This was particularly true for black women, who were 50 percent less likely to struggle with some type of limitation, the study found.

Those eating the highest amounts of dairy products and fruits and vegetables consumed two servings of dairy, three servings of fruit and three servings of vegetables a day. Those eating the lowest amounts ate less than half a serving of dairy and one or less servings of fruits and vegetables a day, the researchers reported.

Currently, dietary recommendations call for three cups a day of low-fat or fat-free dairy products, two cups of fruit and two-and-a-half cups of vegetables, the researchers said.

Houston believes that because fruits and vegetables contain high levels of antioxidants, they can help to prevent cellular damage associated with aging. "Diseases associated with oxidative damage, like cardiovascular disease and cancer, can also lead to functional limitation," she said.

"A diet that's higher in fruit and vegetables and dairy products does have effects other than on chronic conditions like cardiovascular disease and cancer," Houston added. "It is possible that by eating a healthy diet you can also reduce the probability of having functional limitations and disability."

But Dr. David L. Katz, director of the Prevention Research Center at Yale University School of Medicine, said, "This study does not establish cause-and-effect. Both dietary intake, and disability, were self-reported and prone to inaccuracies."

Katz noted that living a healthy lifestyle may have influenced not just diet, but other practices related to risk of disability. "People who take care of themselves in one way tend to be people who take care of themselves in other ways, although attempts were made [by the researchers] to control for this," he said.

Katz added that healthy eating is a good thing whether it reduces the risk of disability or not. "There are health benefits from eating plenty of produce and low- or non-fat dairy. This is true whether or not it's time to add reduced risk of disability to the list."