Regular exercise is one of five things that you can do to lengthen your lifespan.
This was the conclusion of the first study to thoroughly analyze the relationship between "low-risk lifestyle factors" and life expectancy in the United States.
A paper on the research, which was led by the Harvard T.H. Chan School of Public Health in Boston, MA, is shortly to be published in the journal Circulation.
Despite being one of the wealthiest nations in the world, the U.S. is a long way down the list when it comes to life expectancy — in 2015, it ranked 31st.
This might seem startling for a country that spends more on health than any other — that is, until it becomes clear, suggest the new study authors, that most of the money goes on developing drugs and treating disease rather than preventing it.
And yet, many of the most common and costly diseases to treat — such as cancer, cardiovascular diseases, and other chronic conditions — "are largely preventable," they note.
To what extent could a focus on prevention help to raise life expectancy in the U.S., which finds itself averaging 79.3 years, compared with Japan's 83.7?
Lifestyle 'behind 60 percent of early deaths'
Senior study author Frank B. Hu — who is a professor of nutrition and epidemiology at the Harvard T.H. Chan School — and colleagues set out to find some answers by investigating the effect of modifiable health factors.
These are lifestyle behaviors that impact health that individuals can do something about.
They chose to focus on "smoking, excessive alcohol consumption, physical inactivity, poor diet, and obesity," because an analysis of 15 studies covering more than half a million people in 17 nations had concluded that these "unhealthy lifestyle factors" could account for around 60 percent of premature deaths.
The data for the new research came from the Nurses' Health Study and the Health Professionals Follow-Up Study. Both ongoing studies are following thousands of men and women and are collecting information about their diet, lifestyle, medical conditions, and deaths.
The new study used data from 78,865 women over 34 years and from 44,354 men over 27 years.
Five low-risk factors
First, the researchers calculated the extent to which early death in these two cohorts was linked to the following five "lifestyle-related low-risk factors":
- not smoking
- moderate alcohol intake — that is, in the region of up to one 5-ounce glass of wine per day for women, or two for men
- regular exercise, or half an hour or more per day of moderate to vigorous activity
- healthful diet, or being in the top 40 percent of a recognized healthful eating index
- normal weight, or having a body mass index (BMI) under 25
Then, from the 2013–2014 results of National Health and Nutrition Examination Surveys, the team estimated the distribution of the five lifestyle factors across the U.S. population and married it to U.S. death rates from the Centers for Disease Control and Prevention (CDC).
Life expectancy rises with each extra factor
Bringing all the results together, the researchers produced nationally representative estimates of longer life expectancy linked to each low-risk lifestyle factor, and to all of them combined.
They found that women who did not follow any of the five low-risk factors had a life expectancy of 29 years at age 50, compared with 43.1 years for those who adopted all five.
There was a similar pattern for men, with those who did not adopt any of the five factors having a life expectancy of 25.5 years at age 50, compared with 37.6 years for those who adopted all of them.
So, women who stuck to all five low-risk health habits lived an average of 14 years longer than women who followed none of them, and for men, this gain was 12 years.
The team also found a direct relationship between number of low-risk factors followed and reduced risk of early death, with the highest protection coming from sticking to all five.
Life expectancy at the time of birth in the U.S. rose from 63 years in 1940 to 79 years in 2014. The researchers suggest that without widespread obesity, this increase could have been much larger.
Prof. Hu says that in the U.S., "adherence to healthy lifestyle habits is very low," and that public policy should do more to create "healthy food, built, and social environments to support and promote healthy diet and lifestyles."
"This study underscores the importance of following healthy lifestyle habits for improving longevity in the U.S. population."
Prof. Frank B. Hu