30‑Year Harvard Cohort Research Reveals Few People Achieve Full Healthy Ageing

Xinhua News Agency, compiled from foreign media reports. In March 2025, Nature Medicine, a top international journal, published a large‑scale 30‑year cohort study by the Harvard T.H. Chan School of Public Health. Based on long‑term follow‑up data of more than 105,000 participants, the study showed that only 9.3% of subjects met the full criteria for healthy ageing, meaning the vast majority of people cannot maintain sound physical, cognitive and mental health simultaneously in later life.

Conducted using two major long‑term US population databases, the Nurses’ Health Study and the Health Professionals Follow‑up Study, the research had a maximum follow‑up period of 30 years. Moving beyond previous research that merely focused on lifespan, it adopted the World Health Organization framework for healthy ageing and set multi‑dimensional evaluation criteria: freedom from major chronic diseases, intact cognitive function, unimpaired physical mobility and sound mental health. True healthy ageing is achieved only when all four requirements are satisfied, and a long life alone does not equal good health in old age.

According to the research team, many past ageing studies concentrated on the prevention and control of individual diseases, while this research paid more attention to whether older adults can live independently and enjoy a high‑quality life. Statistical results indicated that most participants suffered from at least one problem around the age of 70, including chronic illnesses, memory loss, reduced mobility or depression. Multiple overlapping health conditions were common, and less than 10% maintained comprehensive well‑being in old age.

Dietary pattern stood out as the most prominent modifiable factor affecting healthy ageing observed in the study. Data suggested that people who consistently consumed plenty of whole grains, fresh fruits and vegetables, nuts, legumes and high‑quality unsaturated fats were far more likely to achieve healthy ageing. In contrast, those who ate large amounts of ultra‑processed foods, sugary drinks and processed meat showed a significantly lower chance of meeting healthy‑ageing benchmarks. Participants with the highest adherence to a favourable diet were more than twice as likely to attain healthy ageing compared with those with the lowest adherence. Diets rich in plant‑based foods delivered more prominent protective effects on overall later‑life health.

Notably, the study indicated that genetic factors are not the dominant determinant of healthy ageing. Even people with a family history of longevity can hardly enjoy high‑quality later‑life health if they maintain poor dietary habits in middle age. Researchers explained that ageing‑related damage accumulates gradually starting in middle adulthood. Many cases of old‑age disability and cognitive decline originate from lifestyle habits in mid‑life. Health interventions for later years should therefore begin in middle age, rather than only after illnesses emerge in old age.

Against the backdrop of accelerating global population ageing, public health priorities across countries are shifting from simply extending life expectancy to raising healthy life expectancy. The World Health Organization has repeatedly stressed that healthy ageing does not mean being completely free of illness; its core lies in preserving physical function, cognitive capacity and the ability to take part in social activities. This Harvard study offers practical reference for global geriatric public health: high‑quality later‑life well‑being cannot rely on miracle drugs or longevity genes. Consistent diet and lifestyle habits in middle age represent the key lever accessible to ordinary people.

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