The United States is one of the world’s wealthiest countries, and spends significantly more on health care (per capita) than any other country in the world. However, the life expectancy of Americans is relatively poor (79.3 years) compared to residents of other, comparably wealthy, countries. Lifestyle factors have been implicated as major factors that may contribute to the poor health outcomes. A past meta-analysis (a study of studies) that looked at over 500,000 participants in 17 countries suggested that up to 60% of premature deaths could be due to unhealthy lifestyle factors. Now a new study examines the potential impact of these factors on the American population. The paper, published in Circulation, is entitled “Impact of Healthy Lifestyle Factors on Life Expectancies in the US Population” and is from Yanping Li and colleagues at Harvard’s School of Public Health. The paper has concluded that adopting five simple lifestyle factors can extend your life expectancy by over a decade.
What this study looked at
The authors looked at data from the Nurses’ Health Study (78,865 women over 34 years) and the Health Professionals Follow-up Study (44,354 men over 27 years). These long-standing studies followed thousands of individual who answered periodic questions about medical history, lifestyle, smoking history, exercise frequency, and dietary habits. The five modifiable lifestyle factors studied were:
- Eating a healthy diet – assessed using the Alternate Healthy Eating Index Score, and including scores in the top 40%.
- Maintaining a healthy body weight – a low-risk Body Mass Index (BMI) defined as 18.5 to 24.9 kg/m2.
- Exercising regularly – low risk was estimated at >30 minutes per day of moderate or vigorous exercise (including brisk walking).
- Not drinking excessive alcohol – defined as 5 to 15 g/d for women (about one standardized drink per day) and 5 to 30 g/d for men (up to two drinks per day).
- Smoking history – low risk was defined as never having smoked.
Non-modifiable risk factors like high blood pressure or cholesterol levels were not assessed in this study.
The authors scored each subject as either low risk (score 1) or high risk (score 0). Each subject therefore received a score of 0 to 5, with higher scores indicating a healthier lifestyle. I will not go into the statistical analysis (the paper’s free, online, if someone wants to comment).
What this study found
Here are the characteristics of the patients, stratified by score and study:
The authors noted (edited for clarity):
Each individual component of a healthy lifestyle showed a significant association with risk of total mortality, cancer mortality, and CVD mortality (Table 2). A combination of 5 low-risk lifestyle factors was associated with an HR of 0.26 (95% CI, 0.22–0.31) for all-cause mortality, 0.35 (95% CI, 0.27–0.45) for cancer mortality, and 0.18 (95% CI, 0.12–0.26) for CVD mortality compared with participants with zero low-risk factors. The population-attributable risk of nonadherence to 5 low-risk lifestyle factors was 60.7% (95% CI, 53.6–66.7) for all-cause mortality, 51.7% (95% CI, 37.1–62.9%) for cancer mortality, and 71.7% (95% CI, 58.1–81.0) for cardiovascular mortality. We observed a similar association between the low-risk lifestyle factors and mortality before 75 years of age (Table I in the online-only Data Supplement). The low-risk lifestyle factors were associated with lower risk of cause-specific mortality in women and men similarly.
In Figure 1, below, you can see the life expectancy gain realized based on the number of healthy lifestyle factors in place:
As you can see, all five factors lead to an estimated increase in life expectancy of 14 years (at age 50) for women with the healthiest lifestyles. Men gain an estimated 12 years for those with the healthiest lifestyles. They note:
We estimated that the life expectancy at age 50 years was 29.0 years (95% CI, 28.3-29.8) for women and 25.5 years (95% CI, 24.7-26.2) for men who adopted zero low-risk lifestyle factors. In contrast, for those who adopted all 5 low-risk factors, we projected a life expectancy at age 50 years of 43.1 years (95% CI, 41.3-44.9) for women and 37.6 years (95% CI, 35.8-39.4) for men. The projected life expectancy at age 50 years was on average 14.0 years (95% CI, 11.8-16.2) longer among female Americans with 5 low-risk factors compared with those with zero low-risk factors; for men, the difference was 12.2 years (95% CI, 10.1-14.2).
It’s not all-or-nothing. Even adopting one of the five factors is associated with a beneficial effect that can be measured in years of benefit.
Interestingly, there were a few confounders found. Those with the healthiest lifestyles were more likely to use aspirin (ASA) and less likely to use vitamin supplements.
Simple but not easy
A significant contributor to the overall poor life expectancy of Americans is poor lifestyle-related factors. Following all 5 factors could offer an incremental (to someone aged 50) 14 years of life expectancy for women, and 12.2 years for men, compared with those that have no “low risk” lifestyle features.
If a healthy lifestyle was a drug, it would be the most effective drug ever, and a pharmaceutical company would charge hundreds of thousands of dollars per year for it. But this magical “non-drug” doesn’t come with a long list of side effects – or a price that will bankrupt you. Many of these factors are achievable at modest (or no) cost. You don’t need to eat organic, take supplements, or make drastic dietary restrictions to extend the quantity and quality of your life. If you’re already doing all five of these actions – congratulations! Absent any medical issue that might need treatment, you’re doing everything you possibly can to ensure a long, healthy life.