Women who regularly drank caffeinated coffee in midlife were more likely to age in good physical and mental health, according to a major study that tracked nearly 50,000 participants over three decades.

The research analysed data from 47,513 women in the long-running Nurses’ Health Study, with dietary and health data collected since 1984.

Healthy ageing was defined as living to age 70 or older, being free from 11 major chronic diseases, maintaining physical function, having good mental health, exhibiting no cognitive impairment, and showing no memory complaints.

By 2016, a total of 3,706 women met all the criteria for healthy ageing.

On average, these women consumed 315 mg of caffeine per day between the ages of 45 and 60—roughly the amount in three small cups of coffee or one and a half large cups by today’s standards.

More than 80 percent of their caffeine intake came from regular, caffeinated coffee.

Researchers found that each additional cup of coffee per day was linked to a 2 to 5 percent increase in the odds of ageing healthily, up to a maximum of five small cups per day.

No significant benefits were seen from drinking decaffeinated coffee or tea.

Dr Sara Mahdavi is a postdoctoral fellow at the Harvard T.H. Chan School of Public Health and adjunct professor at the University of Toronto’s Department of Nutritional Sciences.

She said: “While past studies have linked coffee to individual health outcomes, our study is the first to assess coffee’s impact across multiple domains of ageing over three decades.

“The findings suggest that caffeinated coffee—not tea or decaf—may uniquely support aging trajectories that preserve both mental and physical function.”

In contrast, drinking soda was associated with poorer outcomes.

Each additional small glass of soda—another major source of caffeine—was linked to a 20 to 26 percent lower chance of healthy ageing, reinforcing that not all sources of caffeine confer benefits.

Caffeine intake was assessed using validated food frequency questionnaires that included consumption of top contributors of caffeine such as coffee, tea, cola, and decaffeinated coffee.

The analysis adjusted for factors including body weight, smoking, alcohol use, physical activity, education level, and dietary protein intake.

Dr Mahdavi said: “Our study has several key strengths.

“In addition to the large sample size and 30 years of follow-up, we assessed several different aspects of longevity and healthy ageing as well as very comprehensive information on nutritional and lifestyle habits that were collected every four years after the initiation of the study.”

The preliminary results suggest that moderate coffee consumption—up to two cups a day—is likely safe for most people and may offer some health benefits.

But Dr Mahdavi noted that individual responses to caffeine can vary depending on genetics.

The researcher said: “These results, while preliminary, suggest that small, consistent habits can shape long-term health.

“Moderate coffee intake may offer some protective benefits when combined with other healthy behavioudrs such as regular exercise, a healthy diet, and avoiding smoking.

“While this study adds to prior evidence suggesting coffee intake may be linked with healthy aging, the benefits from coffee are relatively modest compared to the impact of overall healthy lifestyle habits and warrant further investigation.”