A new long-term study has found that people who eat diets rich in plant-based foods—and lower in ultra-processed foods—are more likely to age in good health.
Researchers from Harvard T.H. Chan School of Public Health, the University of Copenhagen, and the University of Montreal discovered that certain eating patterns during midlife are linked to a higher chance of reaching age 70 and beyond without major illnesses, while maintaining strong memory, physical function, and mental health.
The study, published in Nature Medicine, is one of the first to explore how diet in midlife affects overall healthy aging—not just lifespan or disease prevention.
“Most studies focus on how diet impacts specific diseases or how long people live,” said co-author Dr. Frank Hu from Harvard. “Our study takes a broader view, asking: how does what we eat affect our ability to enjoy life and stay independent as we age?”
Researchers used health data from over 105,000 men and women between the ages of 39 and 69 who were tracked for 30 years as part of the Nurses’ Health Study and the Health Professionals Follow-Up Study.
Every few years, participants filled out detailed questionnaires about their diets, which researchers scored based on how well they followed eight different healthy eating patterns.
These eating patterns included:
- Alternative Healthy Eating Index (AHEI)
- Mediterranean-style diets (aMED and DASH)
- MIND diet (designed to support brain health)
- Healthful plant-based diet index (hPDI)
- Planetary Health Diet Index (PHDI), which includes environmental sustainability
- Two patterns based on avoiding foods that cause inflammation or spike insulin levels (EDIP and EDIH)
Most of these diets focus on eating more fruits, vegetables, whole grains, legumes, nuts, and healthy fats. Some also include small to moderate amounts of healthy animal-based foods, such as fish and low-fat dairy. They all discourage eating large amounts of red meat, processed foods, sugary drinks, and refined grains.
Out of all participants, 9,771 people (about 9.3%) aged healthfully. This means they reached age 70 without serious chronic diseases and maintained their memory, physical ability, and mental well-being.
Among the different diets, the AHEI stood out. People who followed it most closely had an 86% higher chance of healthy aging at age 70 and more than double the chance of healthy aging at age 75 compared to those who followed it the least. The AHEI diet includes lots of whole, plant-based foods and avoids red meats, sugary drinks, and overly salty or refined foods.
Another strong performer was the Planetary Health Diet (PHDI), which not only benefits human health but also considers the environment by recommending fewer animal-based foods.
On the other hand, high intake of ultra-processed foods—especially processed meats, sugary sodas, and even artificially sweetened diet drinks—was linked to a lower chance of healthy aging. Ultra-processed foods often include added sugars, unhealthy fats, and artificial ingredients, which have been shown in past research to negatively affect health.
“Since most people want to stay active and independent as they get older, understanding how diet plays a role is important for both individuals and public health,” said co-author Dr. Marta Guasch-Ferré of the University of Copenhagen and Harvard.
The researchers emphasized that there is no single “perfect” diet that fits everyone. What matters is the overall quality of the diet and how well it supports long-term health. “Healthy diets can and should be flexible,” said lead author Dr. Anne-Julie Tessier. “They can be adapted to fit different lifestyles, preferences, and cultures.”
Review and Analysis
This study offers strong evidence that healthy aging is not just about genes or luck—what we eat in midlife matters. The findings suggest that sticking to a diet rich in plant-based foods and cutting back on highly processed foods can help people stay healthier as they age.
One of the most valuable parts of this research is its focus on quality of life, not just avoiding disease or living longer. Many older adults fear losing their independence or mental sharpness more than getting a diagnosis. This study shows that diet may help preserve those abilities too.
It’s also important to note that many of the best-performing diets in the study are not strict or extreme. They don’t require cutting out all animal products or following complicated food rules. Instead, they simply prioritize whole foods—especially plants—and minimize processed or sugary options.
However, the study does have some limits. Most of the people involved were health professionals, meaning they may already be more health-conscious than the general population. More research is needed in diverse groups, including people from different economic, racial, and cultural backgrounds.
Still, these findings offer helpful guidance: eating well during midlife may set the stage for a healthier, more active old age. Small changes now—like adding more vegetables, cutting back on soda, or choosing whole grains—could have long-lasting effects later in life.
If you care about nutrition, please read studies about a breakfast linked to better blood vessel health, and drinking too much coffee could harm people with high blood pressure.
For more information about health, please see recent studies about unhealthy habits that may increase high blood pressure risk, and results showing plant-based protein foods may help reverse diabetes.
The research findings can be found in Nature Medicine.
Copyright © 2025 Knowridge Science Report. All rights reserved.
