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A new large-scale study reveals that diet plays a key role in ageing well. Researchers followed people’s eating habits from midlife to around age 70. Their findings link plant-based diets to better physical and mental health later in life.

Plant-Based Diets Linked to Healthier Ageing

The study, published in Nature Medicine, observed about 105,000 people in the United States over nearly 30 years. It examined the health impact of eight popular diets. These included the Mediterranean diet and the DASH plan, which limits salt to manage blood pressure.

Participants with the best health outcomes ate mostly fruits, vegetables, whole grains, nuts, legumes, and unsaturated fats. They also consumed moderate amounts of animal-based foods, such as low-fat dairy. They avoided red and processed meats, sugary drinks, ultra-processed snacks, and trans fats.

Trans fats are common in fried foods. The healthiest participants also limited sodium intake.

“There’s not one perfect diet,” said Marta Guasch-Ferré, the study’s senior author. She is a lifestyle and chronic disease researcher at the University of Copenhagen. “But different diets can improve our health,” she added.

She emphasized that healthy diets are not one-size-fits-all.

Less Than 10% Reach Old Age in Good Health

Although diet and health have been widely studied, this research focuses on long-term diet patterns and their link to overall ageing. People in the study were considered healthy if they reached 70 without major chronic diseases. They also needed to maintain good brain function, mental health, and physical ability.

This approach looks beyond lifespan. It focuses on the quality of life in old age.

“Do we really want to live longer, or do we want to live better?” Guasch-Ferré asked.

The answer, according to the study, is clear. But only a small group—fewer than 1 in 10—met the criteria for healthy ageing.

While the study focused on U.S. participants, Guasch-Ferré believes the results apply in Europe too. The researchers adjusted for income and education levels. Still, they acknowledged that genetics, environment, and healthcare access also affect health outcomes.

Even with these variables, the study’s findings could inform dietary guidelines. They may also encourage people to make healthier food choices.

“Of course, healthy ageing is not just about diet,” Guasch-Ferré said. “But even small changes in eating habits can help.”