Healthy midlife diet linked to higher chances of aging well, study finds

A new study suggests that maintaining a healthy, plant-forward diet in midlife is associated with a greater likelihood of aging in good overall health. Researchers from the Harvard T.H. Chan School of Public Health, University of Copenhagen, and University of Montreal found that adults who adhered to certain dietary patterns between the ages of 39 and 69 were more likely to reach age 70 free from major chronic diseases and with preserved cognitive, physical, and mental health.

The study, published 24 March 2025 in Nature Medicine, is one of the first to examine how dietary patterns in midlife influence broader measures of healthy aging – not only disease prevention or longevity, but also quality of life and functional independence in older age.

“Studies have previously investigated dietary patterns in the context of specific diseases or how long people live. Ours takes a multifaceted view, asking, how does diet impact people’s ability to live independently and enjoy a good quality of life as they age?” commented Frank Hu, co-corresponding author and Chair of the Department of Nutrition at Harvard Chan School.

Using data from two large cohorts – the Nurses’ Health Study and the Health Professionals Follow-Up Study – the researchers tracked the health and dietary habits of over 105,000 participants over a 30-year period. Participants completed regular dietary questionnaires, which were evaluated against eight healthy eating patterns. These included the Alternative Healthy Eating Index (AHEI), the Alternative Mediterranean Index (aMED), the Dietary Approaches to Stop Hypertension (DASH), the Mediterranean-DASH Intervention for Neurodegenerative Delay (MIND), the healthful plant-based diet (hPDI), the Planetary Health Diet Index (PHDI), the empirically developed inflammatory dietary pattern (EDIP), and the empirical dietary index for hyperinsulinemia (EDIH).

Each pattern emphasized high consumption of fruits, vegetables, whole grains, legumes, nuts, and unsaturated fats. Several also included low to moderate intake of healthy animal-based foods such as fish and certain dairy products. The study also considered participants’ intake of ultra-processed foods – defined as industrially manufactured items containing artificial ingredients, added sugars, unhealthy fats, and high sodium.

Among all participants, 9.3% – amounting to 9,771 individuals – achieved what the study defined as “healthy aging.” This group reached at least age 70 with no major chronic disease diagnoses and maintained strong cognitive function, physical ability, and mental well-being.

Of the dietary patterns studied, the AHEI was most strongly associated with healthy aging. Participants with the highest adherence to this diet had an 86% higher likelihood of reaching age 70 in good health compared to those with the lowest adherence. They also had more than double the likelihood of healthy aging by age 75. The AHEI emphasizes a diet rich in whole plant foods, healthy fats, and minimal intake of red and processed meats, sugary beverages, and refined grains.

The Planetary Health Diet Index, which considers the environmental sustainability of food choices alongside human health, also showed a strong positive link with healthy aging. This diet is centered on plant-based foods while minimizing consumption of animal-based products.

Conversely, high intake of ultra-processed foods, particularly processed meats and both sugary and artificially sweetened beverages, was associated with a reduced likelihood of aging healthfully.

“Since staying active and independent is a priority for both individuals and public health, research on healthy aging is essential,” added Marta Guasch-Ferré, co-corresponding author and Associate Professor at the University of Copenhagen. “Our findings suggest that dietary patterns rich in plant-based foods, with moderate inclusion of healthy animal-based foods, may promote overall healthy aging and help shape future dietary guidelines.”

The study’s lead author, Anne-Julie Tessier of the University of Montreal and the Montreal Heart Institute, noted that flexibility in dietary approaches is important. “Our findings also show that there is no one-size-fits-all diet. Healthy diets can be adapted to fit individual needs and preferences,” she said.

The study’s authors acknowledged limitations, particularly that the study populations included only health professionals, who may not represent broader demographics. They noted that future research should include individuals from more diverse socioeconomic and ancestral backgrounds to better assess the generalizability of the findings.

The research was supported by grants from the National Institutes of Health, the Canadian Institutes of Health Research, the United States Department of Agriculture, the Novo Nordisk Foundation, and other institutions.