Li Y, Schoufour J, Wang DD, Dhana K, Pan A, Liu X et al. Healthy lifestyle and life expectancy free of cancer, cardiovascular disease, and type 2 diabetes: prospective cohort study. BMJ. 2020 Jan 8;368:l6669. doi: 10.1136/bmj.l6669.
At a glance
A recent prospective cohort study published in BMJ reports that adherence to a healthy lifestyle is associated with longer life expectancy and without most chronic diseases such as cancer, cardiovascular disease and type 2 diabetes.
The behaviours and indices analysed concern diet, tobacco smoking, physical activity, alcohol consumption and body mass index (BMI).
What is already known
We know that modifiable lifestyle behaviours and factors such as smoking, physical activity, alcohol consumption, body weight and dietary quality have a decisive influence on both total life expectancy and the incidence of chronic diseases.
However, few studies have fully examined how a combination of several lifestyle factors can be related to life expectancy without major chronic diseases such as type 2 diabetes, cardiovascular disease and different types of cancer.
Design and Method
This is an observational study that reports the results of two large cohorts. The researchers reported the results of prospective cohort studies NHS (Nurses’ Health Study) and HPFS (Health Professionals Follow-up Study) conducted on nurses and other health professionals in the USA.
For this analysis, a baseline was established at 1980 for NHS and 1986 for HPFS. In both cohorts, a self-administered questionnaire was sent every two years to update the information and identify newly diagnosed cases of various diseases. Five lifestyle factors (diet, smoking, physical activity, alcohol consumption and BMI) were investigated.
Data from subjects who had already developed one of the diseases included in the outcomes of the study (cancer, cardiovascular disease and type 2 diabetes) and those who failed to report the required data were excluded from the analysis. The data of 111,562 subjects (73,196 women and 38,366 men) were analysed.
Adopting 4 or 5 healthy lifestyle factors, among those investigated, increases life expectancy without diseases such as type 2 diabetes, cardiovascular disease and cancer, by 10.6 years for women and 7.6 years for men.
Specifically, life expectancy free from the above classes of pathologies, at the age of 50, was of:
- 34.4 years for women who had adopted 4 or 5 healthy lifestyle factors;
- 23.7 years for women who had not adopted healthy lifestyle factors;
- 31.1 years for men who had adopted 4 or 5 healthy lifestyle factors;
- 23.5 years for men who had not adopted healthy lifestyle factors.
This research, in accordance with the results of previous studies, confirms that a healthier lifestyle is associated with an increase in total life expectancy and life expectancy free of cancer, cardiovascular disease and type 2 diabetes.
Its main point is the ability to follow changes in lifestyle factors in a dynamic way over time. The main strengths are:
- long-term follow-up;
- the sample size of the two cohorts:
- the low drop-out rate;
- detailed and repeated lifestyle measurements.
The study certainly presents the limitations of all studies using self-administered questionnaires that may report distorted or incorrect data.
In addition, the association between five lifestyle factors and years of living without cancer, cardiovascular disease and type 2 diabetes was investigated, leaving aside other major classes of chronic diseases (respiratory, renal, etc.) and the variation in lifestyle following diseases diagnosed after the first questionnaire was not investigated.
It should also be noted that the study is only conducted on health professionals, who should already have healthier lifestyles than the average population.
What the prospects
Further research efforts are needed to confirm the results presented and to expand the strength of the evidence, including more lifestyle factors and more outcomes.
However, there are clear indications that public policies should increasingly act on citizens to promote the adoption of a healthy diet and all those healthy lifestyle behaviours described here.
A further reflection should be made as this study can lead to reflections in the training field, about the need to increase training moments, inherent to the Lifestyle medicine sector, addressed both to health professionals and to the population in general.
By Carmela Rinaldi