Women who eat more fiber and high-quality carbohydrates in midlife are more likely to be cognitively and physically healthy in their old age, a large new study suggests.

While there’s a lot of evidence showing how diet affects longevity and the risk for chronic diseases, the new study focused on how what we eat influences quality of life as we age, according to the report published in JAMA Network Open.

Researchers at the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University, analyzed diet data from 47,512 women who were participants of the long-running Nurses’ Health Study, one of the most respected and largest investigations into causes of chronic diseases in women. 

Every four years, between 1984 and 2016, the participants filled out a questionnaire that asked how frequently 130 foods had been consumed over the past year. The options ranged from never to six times a day.

The researchers centered on dietary data collected in 1984 and 1986, as this was when the women were at midlife.

“The primary high-quality carbohydrates were whole grains, whole fruits and vegetables and legumes,” scientist Andres Ardisson Korat, lead author of the new research, said. “The reason is they have a lot of fiber and a lot more resistant forms of starches that break down more slowly in our bodies. Low quality carbohydrates included refined grains and added sugars.”

Resistant forms of starch, such as beans and legumes and whole grain, don’t cause blood glucose levels to spike, plus they increase the feeling of fullness and are high in fiber. 

The researchers defined healthy aging as surviving to age 70 while being free of 11 major chronic diseases, including cancer, diabetes, stroke, arthritis and osteoporosis; having no impairment in memory or physical function; and being in good mental health.

The dietary analysis revealed a 31% greater likelihood of healthy aging among women who ate high-quality carbs, while a diet heavy in low-quality carbs was associated with a 13% lower likelihood of healthy aging.

Ardisson Korat said healthy aging is someone with a positive score in four areas:

No major chronic disease.

Good physical health.

Good cognitive function.

Good mental health.

“A person with good physical health, for example, would be able to lift and carry groceries, climb a flight of stairs and walk a certain distance,” Ardisson Korat said.

Among the participants in the new study, only 3,706 reached age 70 free of chronic diseases. Ardisson Korat was surprised that so few women accomplished it, but noted a 2024 Tufts study on women’s consumption of protein showed similar findings. In Ardisson Korat’s protein research, women who ate more plant proteins were 46% more likely to be healthy into their later years, while women who ate more animal protein, such as beef, chicken, milk, fish and cheese were 6% less likely to stay healthy as they aged.

A limitation of the new study is that it didn’t explore how high-quality carbohydrates could lead to a healthier old age. Also, the participants in the Nurses Health Study are mostly white women and the findings may not be representative of the broader population.

It’s significant, however, because the researchers looked at how diet can have an impact on overall healthy aging, experts said.

Brooke Aggarwal, an associate professor of medical sciences in the division of cardiology at the Columbia University Vagelos College of Physicians and Surgeons, said the researchers focused on a really critical period in women’s lives to suggest intervention.

“This shows with better attention to diet we might have a good quality of life: Can someone think clearly? Can they physically function well? Can they get in and out of bed by themselves,” Aggarwal said.

Other studies have shown that diets high in fiber can have a positive impact on outcomes, such as diabetes and other chronic diseases, said Dr. Gül Bahtiyar, chief of the division of endocrinology, diabetes and metabolism at NYC Health+Hospitals/Woodhull.

But a strength of the study is that it is “huge,” said Bahtiyar, who was not involved in the research.

Heidi Silver, director of the Vanderbilt Diet, Body Composition, and Human Metabolism Core at the Vanderbilt University Medical Center, said the data in the new study showed that fruit was especially good for healthy aging.

“Fruits are a good source of vitamins and minerals,” said Silver, who was not involved in the research. “There’s such as wide range of micro nutrients in them. You don’t get that from a lot of the other food groups.”

If people want to eat healthier, what would Silver suggest?

“I would recommend eating a variety of fruits,” she said. “But they should at least eat two pieces of fruit a day.”