A new study published in Nature Medicine highlights another benefit of eating more plant-based and less processed foods: healthy aging. While previous research has linked such diets to a lower risk of hypertension, stroke, and diabetes, this study shows a strong connection between healthy eating and maintaining physical and mental well-being into older age.
“What makes this study unique is that it examines the overall impact of healthy eating on aging, not just on disease prevention,” said Dr. Frank B. Hu, professor and chair of the Department of Nutrition at the Harvard T.H. Chan School of Public Health and co-author of the study.
Diet Benefits Independent of Lifestyle Factors
Dr. Hu emphasized that even without perfect lifestyle habits, a healthy diet can offer independent benefits. “This finding is important because it shows that regardless of body weight, smoking habits, or exercise levels, diet alone can support healthy aging,” he said.
Study Details and Findings
The research team studied more than 105,000 men and women aged 39 to 69 over a 30-year period. Participants completed surveys every four years that assessed their diets, exercise, sleep, smoking habits, cognitive function, and mental health. The team examined adherence to eight dietary patterns, including the plant-based diet, DASH diet, and MIND diet.
By age 70, 9.3% of participants had aged healthfully—meaning they had no major chronic disease and maintained good physical, mental, and cognitive health. The study found that better adherence to balanced diets in midlife increased the chances of healthy aging.
Participants who closely followed the Alternative Healthy Eating Index (AHEI) diet had an 86% higher chance of being healthy at age 70 and were more than twice as likely to age healthfully by 75. Those following the Planetary Health Diet Index (PHDI), which focuses on plant-based foods and limits animal products, also showed strong results. In contrast, diets high in ultra-processed foods and sugary drinks were linked to lower chances of healthy aging.
What These Diets Include
The AHEI diet promotes eating fruits, vegetables, whole grains, nuts, legumes, and healthy fats. It includes moderate amounts of lean animal proteins like fish and poultry while limiting red and processed meats. The diet also follows the Healthy Eating Plate model: half the plate should be fruits and vegetables, one-quarter whole grains, and one-quarter healthy proteins.
“This isn’t an extreme or rigid diet,” said Dr. Hu. “It’s flexible and based on making balanced choices.” Beverages such as water, tea, and coffee are encouraged, while sugary drinks and excessive dairy should be limited.
Registered dietitian Ginger Hultin adds that applying the model is simple. For example, a breakfast of a whole grain tortilla with eggs or tofu, vegetables like spinach and mushrooms, and a piece of fruit fits the model well.
The PHDI diet is similar but places more emphasis on plant-based foods and further reduces animal-based products, especially red meat. This approach benefits both personal health and the environment.
Why These Diets Help With Aging
“Both diets are rich in fiber and natural compounds from plants, and low in saturated fat and added sugar,” said Hultin. “This supports healthy blood pressure, cholesterol, blood sugar levels, and reduces chronic inflammation.”
Keeping inflammation low is key, as it can reduce the risk of chronic conditions like arthritis, Parkinson’s disease, Crohn’s disease, and even depression. These illnesses can significantly impact quality of life in older age.
The Takeaway
Adopting healthy eating habits—especially diets rich in plant-based foods—can help you live longer and maintain better health as you age. “It’s not just about living longer, but about having a better quality of life,” Dr. Hu said.
Importantly, there’s no need to follow a strict diet to see benefits. “You can mix and match nutritious foods that you enjoy,” Dr. Hu added. “What matters most is building a sustainable pattern of healthy eating.” However, he stressed that diet is one part of a larger lifestyle and should be combined with regular exercise and other healthy habits.
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