A person wearing tennis shoes walks outside on a trail.
Thirty minutes of daily exercise is an investment that can pay off in dividends years from now. (For Spectrum Health Beat)

Middle-aged Americans who are exercising and eating right, give yourselves a pat on the back: Your efforts will pay off, new research shows.

A study involving more than 110,000 people finds that a healthy lifestyle in middle age appeared to help folks live longer lives free of major diseases.

Researchers at the Harvard T.H. Chan School of Public Health said that many prior studies have made the connection between healthy living and reductions in a person’s odds for cancer, heart disease and other ills.

However, “few studies have looked at the effects of lifestyle factors on life expectancy free from such diseases,” lead researcher Yanping Li, a senior research scientist in nutrition, said in a Harvard news release.

To see if a healthier middle age could lead to a long, disease-free old age, Li and her team tracked health data on U.S. nurses and other health professionals, more than 73,000 women and more than 38,000 men. Each participant was given a “healthy lifestyle score,” ranging from 0 to 5, with 5 indicating the healthiest lifestyle.

The score was based on the person’s adherence to five low-risk lifestyle factors: never smoking, maintaining a healthy weight, getting at least 30 minutes of daily physical activity, moderate alcohol intake and a having a good-quality diet.

The participants were assessed regularly over a period of more than 20 years.

The research team adjusted their results for factors such as the person’s age, ethnicity and family medical history.

The study found that a woman aged 50 years of age could expect 24 more years of life that was free from cancer, heart disease and diabetes if she had none of the healthy lifestyle factors on that list of five.

But that same woman could expect another decade of healthy life—34 years—if she had four or five of those healthy factors, the researchers said.

Among men, life expectancy free of any of the three major diseases was 24 years for those with no low-risk lifestyle factors and 31 years for those with four or five low-risk lifestyle factors.

Men who smoked heavily (15 or more cigarettes a day) and obese men and women had the lowest rates (75% or less) of disease-free life expectancy at age 50, the study found.

The study was published recently in the BMJ.

The researchers noted that this is an observational study, so it couldn’t prove cause and effect.

However, it did include a large number of people who underwent detailed and repeated assessments of lifestyle factors over a long period of time.

Beyond individuals making the decision to live healthier, societies can do their part to encourage such changes, senior researcher Dr. Frank Hu said in the news release.

“Given the high cost of chronic disease treatment, public policies to promote a healthy lifestyle by improving food and physical environments would help to reduce health care costs and improve quality of life,” said Hu, who is chair of the department of nutrition at Harvard.