What people eat at 40 could affect health decades later, Harvard study shows

NEW YORK, July 2 (UPI) -- What people eat at age 40 could affect the quality of their lives at age 70, a new Harvard study reveals.

The findings were presented Tuesday at the American Society for Nutrition's annual meeting in Chicago.

In the study, investigators found that people who followed a healthy diet from their 40s onward were 43% to 84% more likely to function well physically and mentally at age 70 compared with those who did not follow such a diet.

The research, based on data from more than 100,000 people in Harvard's Nurses' Health Study and Health Professionals Follow-Up Study, spanned 30 years.

"Diet is a leading factor in chronic disease prevention, yet few studies have examined and compared healthy diets and overall healthy aging encompassing cognition, physical and mental health," the study's lead author, Anne-Julie Tessier, told UPI via email.

Higher consumption of fruits, vegetables, whole grains, unsaturated fats, nuts, legumes and low-fat dairy was associated with greater odds of healthy aging. In contrast, higher intakes of trans fat, sodium and total meats, including processed meat, were associated with lower odds of healthy aging.

The study's authors said their research was unique because it focused on healthy aging, which they defined not only as the absence of disease, but also the ability to live independently and enjoy a good quality of life as people grow older.

"Traditionally, dietary guidelines have focused on preventing chronic diseases like heart disease," said Tessier, a research associate in the Department of Nutrition at T.H. Chan School of Public Health in Boston. She is a registered dietitian with a doctorate in nutrition.

She noted that the study's results "will serve to inform public health recommendations in emphasizing the importance of diet in midlife for promoting overall healthy aging."

Researchers analyzed data from more than 106,000 people dating to 1986. Participants were at least 39 years old and free of chronic diseases at the outset of the study. Every four years, they answered questionnaires about their diet.

As of 2016, almost half of the study's participants had died and only 9.2% survived to age 70 or older while avoiding chronic diseases and maintaining good physical, cognitive and mental health.

Researchers compared rates of healthy aging among people in the highest versus lowest quintiles for complying with each of eight healthy dietary patterns defined by earlier studies.

They observed the strongest correlation with the alternative healthy eating index, a pattern reflecting close adherence to the Dietary Guidelines for Americans. Participants ranking in the top quintile for this dietary pattern were 84% more likely to attain healthy aging than those in the bottom quintile.

Various diets also correlated strongly with healthy aging -- hyperinsulinemia diet (associated with a 78% greater likelihood of healthy aging), planetary health diet (68%), alternative Mediterranean diet (67%), dietary approaches to stop hypertension (DASH) diet (66%), the Mediterranean-DASH intervention for neurodegenerative delay (MIND) diet (59%) and empirical dietary inflammatory pattern (58%).

There was a somewhat more modest association for the healthful plant-based diet (43%).

"A novel finding was the association between the planetary health diet and healthy aging," Tessier said. "This diet is based on the EAT Lancet Commission's report, which emphasizes fruits, vegetables, whole grains, plant proteins and healthy fats from sustainable sources.

"The fact that it emerged as one of the leading dietary patterns associated with healthy aging is particularly interesting because it supports that we can eat a diet that may benefit both our health and the planet."

The ties between diet and healthy aging remained robust even after adjustment for other lifestyle factors known to influence health and socioeconomic status, Tessler noted.

She added that each healthy dietary pattern was linked with overall healthy aging, as well as with individual components of healthy aging, including physical health, cognitive functioning and mental health.

Given the study's emphasis on middle-age dietary patterns, she said future research could shed light on the potential impacts of switching to a healthier plan later in life.

"These findings reinforce many well-established dietary approaches that have been associated with improved health, said Kelly Kane, a registered dietitian and director of nutrition at Tufts Medical Center in Boston. She was not involved in the study.

"For example, the DASH diet (Dietary Approaches to Stop Hypertension) has been associated with lower blood pressure," she said.

Confirming the significance of a diet rich in fruits, vegetables and whole grains corresponds with other recommendations for healthy aging, as well as minimizing risk and treating chronic diseases, such as hypertension, cardiovascular disease and diabetes, Kane said.

"This study provides more insight into the specifics of the various patterns that can have the greatest health impact," she said. "However, the difficult part is applying these patterns to actual eating and dietary choices to reflect real-world eating."

Kane recommended consulting with a registered dietitian to adapt eating habits that would align more closely with these healthy patterns.

More studies of this kind would provide "alternative reasoning for why a healthy diet across the lifespan is so important," said Jacquelyn Davis, a registered dietitian and clinical nutrition manager at Bridgeport Hospital in Bridgeport, Conn.

While previous research focused mainly on chronic disease prevention, this new study emphasizes a healthy diet's contribution to aging healthy and living independently with advancing age, Davis said.

"This can be a motivator for individuals to make changes to their eating habits outside of disease risk," she said.

However, Dr. Jane Orient, executive director of the Association of American Physicians and Surgeons, said she would take this study "with a grain of salt" due to many confounding variables, including salt, calories, vitamins, socioeconomic status, education level and occupation.

"There has been a great change over 30 years in what is considered a healthy diet -- margarine versus butter, for example, or low-fat versus low-arb," said Orient, a general internal medicine practitioner in Tucson, Ariz.

The jury is still out on the best diet, she said, adding, "Are Boomers who grew up on home cooking better off than those eating primarily 'convenience' foods plus tons of snack foods today? The study, unfortunately, can't answer that."