Coffee, and whether or not it’s good for you, has been a research focus for decades. A regular cup or two has been linked to better heart health, a longer life, and most recently, a study led by a Harvard researcher, Dr. Sara Mahdavi found that drinking coffee may even aid healthy aging in women.

“The findings suggest that caffeinated coffee—not tea or decaf—may uniquely support aging trajectories that preserve both mental and physical function,” said Mahdavi, a postdoctoral fellow at Harvard T.H. Chan School of Public Health.

The paper, which was presented at the American Society of Nutrition’s annual meeting, has not yet been published or peer-reviewed. But the findings are robust.

Researchers followed 47,513 women over the course of decades, starting in 1984, and analyzed their health data and coffee-drinking habits.

By 2016, only 3,706 participants were considered healthy agers. Factors that the researchers considered to define healthy aging were:

Being 70 or older

Not having 11 chronic diseases, including heart disease, Type 2 diabetes and cancer

Reporting positive mental health

Being able to maintain physical function

Not having memory issues or cognitive impairment

The researchers considered additional lifestyle factors like smoking, exercise frequency and diet, and adjusted for their contribution to health outcomes.

Participants were also asked to share how often they drank coffee, tea and either Coca-Cola or Pepsi, which can all be sources of caffeine. Women who had at least one cup of coffee daily were more likely to be among the healthy agers, the study found.

Of the healthy agers, each extra cup of coffee they had each day was associated with a 2% to 5% increased chance of aging well, peaking at about five small cups a day.