Older adults who follow dietary guidelines tend to have a better quality of life and less trouble getting around and taking care of themselves, according to a new study.

Not many prior studies had tried to tackle that issue, researchers said.

"Our paper showed that maintaining an overall optimal diet quality will be beneficial for preserving the general well-being of older adults," lead author Bamini Gopinath said in an email.

Gopinath is a senior research fellow with the Westmead Millennium Institute for Medical Research at the University of Sydney in New South Wales, Australia.

"Adhering to national dietary guidelines which is typified by high intake of fruits, vegetables, whole grains, and fish could be beneficial in maintaining a good quality of life and functional ability such as shopping, household duties, meal preparation, and taking their own medication," she said.

Her study included 1,305 men and women age 55 and over that were part of a large Australian study of common eye diseases and general health.

Participants filled out questionnaires about what they ate and how often in 1992 to 1994. Researchers scored each person's diet on a scale from 0 to 20 based the Australian Guide to Healthy Eating. Higher scores indicated better diets.

The one-quarter of participants with the highest-quality diets had scores above 11.1. The one-quarter with the poorest diets scored 8.1 and below, the researchers reported in the Journal of the Academy of Nutrition and Dietetics.

Five and ten years after reporting on their diets, participants completed surveys assessing their quality of life with regard to physical health, mental health, social functioning and vitality. Each area was measured on a scale of 0 to 100.

On average, participants with the highest diet scores also reported a better quality of life.

Physical function was almost six points higher among the healthiest eaters than the least healthy. General health was four points higher among healthy eaters and vitality was five points higher.

However, there were no differences on measures of mental health or social functioning, based on diet.

The researchers also assessed how well people could perform basic and instrumental activities of daily living 10 and 15 years after the diet surveys.

Basic activities include being able to eat, dress and groom without assistance and the ability to walk alone. Instrumental activities include the ability to go shopping, use a telephone, handle money and travel beyond walking distance.

There was no difference in how well people performed basic activities of daily living based on their diets. But participants with the highest diet scores were half as likely to be impaired when it came to instrumental activities compared to those with the worst diets.

The findings don't prove diet, itself, was responsible for the differences in quality of life and how well people performed daily tasks.

But Gopinath believes they could contribute to the evidence needed to come up with strategies that help an aging population make dietary changes.

"If older adults didn't make healthy choices when they were younger, they may need to change their habits to get the necessary nutrients for a better quality of life. In fact, many older adults are coming up short, when it comes to essential vitamins, minerals, and fiber," Ruth Frechman said in an email.

She is a registered dietitian and spokesperson for the Academy of Nutrition and Dietetics and was not involved in the study.

Frechman said people can turn to the U.S. Department of Agriculture's MyPlate guide for help with healthy eating.

"To reduce the risk of heart disease and cancer, half of the grains should be whole grains, such as whole grain pasta, brown rice or oatmeal. It's also important to include low-fat or fat-free sources of dairy for healthy bones," she added.