January 08, 2020
People who adopt up to five low risk lifestyle factors have a substantially longer life expectancy free of major chronic disease at 50 years of age compared with those who follow none of them, say US researchers.
Yanping Li, MD, PhD, and colleagues, who examined data on over 110,000 female and male healthcare professionals who took part in two landmark studies, are calling for better public health policies to improve the food and physical environment.
They found that women who followed four of five low-risk lifestyle factors had a life expectancy free of cancer, cardiovascular disease, and type 2 diabetes at 50 years that was over 10 years longer than women who followed none.
And the research, published online January 8 in BMJ, indicates that, in men, the gain in disease-free life expectancy approached 8 years.
The results "suggest that promotion of a healthy lifestyle would help to reduce the healthcare burdens through lowering the risk of developing multiple chronic diseases ... and extending disease-free life expectancy," say the authors.
Critical to this are "public policies for improving food and the physical environment conducive to adopting a healthy diet and lifestyle, as well as relevant policies and regulations (for example, smoking ban in public places or trans-fat restrictions)."
Study Extends Previous Findings
A multitude of studies in recent years have shown that the increase in average life expectancy has led to an increase in the prevalence of chronic diseases such as type 2 diabetes, cardiovascular disease, and cancer.
Although modifiable lifestyle factors, including smoking, physical activity, alcohol intake, body weight, and diet, are linked to changes in life expectancy and incidence of chronic disease, there has been little research into how combinations of such factors may affect disease-free life expectancy.
"Our study extends previous findings by comprehensively assessing five lifestyle risk factors and three major chronic diseases in combination and by providing broader estimates of longevity and the number of years lived with and without disease in relation to lifestyle factors individually and in combination," write Li, of the Department of Nutrition, Harvard T.H. Chan School of Public Health, Boston, Massachusetts, and colleagues.
They studied data on 73,196 women enrolled in the Nurses' Health Study between 1980 and 2014, and 38,366 men from the Health Professionals Follow-Up Study, recruited between 1986 and 2014.
All participants completed questionnaires on medical, lifestyle, and other health-related variables, and the researchers excluded individuals already diagnosed with cancer, cardiovascular disease, or type 2 diabetes.
They then created a healthy lifestyle score based on five factors:
- Diet, as assessed using the Alternate Healthy Eating Index, with a score in the upper 40% indicating a healthy diet;
- Smoking (never vs ever);
- Moderate to vigorous physical activity (≥ 30 minutes/day);
- Moderate alcohol consumption (5-15 g/day for women, 5-30 g/day for men); and
- Body mass index (18.5-24.9 kg/m2).
The healthy lifestyle score ranged from 0 to 5; individuals received a score of 1 if they met the criterion for low risk for each lifestyle factor and a score of 0 otherwise.
Over the course of the study, for women, there were 2,270,411 person-years of follow-up and 21,344 deaths. For men, there were 930,201 person-years of follow-up and 13,039 deaths.
At 50 years of age, total life expectancy increased alongside the healthy lifestyle score, from 31.7 years to 41.1 years in women and from 31.3 years to 39.4 years in men.
Life expectancy free of cancer, cardiovascular disease, and type 2 diabetes at 50 years of age ranged from 23.7 years among women who adopted no low-risk lifestyle factors to 34.4 years in women who adopted four or five factors.
In men aged 50 years, life expectancy free of cancer, cardiovascular disease, and type 2 diabetes ranged from 23.5 years among those adopting no low-risk lifestyle factors to 31.1 years in those who adopted four or five.
Analysis revealed that women with four or five low-risk lifestyle factors gained 10.6 years of life expectancy free of the three major chronic diseases compared with women with no factors, while men gained 7.6 years.
Observational Study But Message Likely Applies Broadly
Digging deeper into the individual diseases, the researchers found that four or five lifestyle factors were associated with a longer life expectancy without cancer — versus no factors — of 8.3 years in women and 6.0 years in men.
For cardiovascular disease, the gain in life expectancy was 10.0 years in women and 8.6 years in men, and was greatest for type 2 diabetes, at 12.3 years in women and 10.3 years in men.
The lowest life expectancy free of the three major diseases was seen in men who smoked at least 15 cigarettes per day, and obese men and women, with 75% or lower life expectancy at 50 years lived disease-free.
The authors acknowledge the study was observational, relying on self-reported lifestyle habits, and most participants were white health professionals, and so the results may not be generalizable.
"Therefore, further studies are warranted to replicate our findings in other ethnic and racial groups and people with other professional backgrounds," they write.
"However, the biologic effects of unhealthy behaviors are likely to apply to other populations, and the relative homogeneity of the study populations in educational attainment, health awareness, and socioeconomic status reduces residual confounding and enhances the internal validity," they conclude.