Lifebrain Monthly E-newsletter November 2020
 

Socio-economic status and health

How to measure health?

Life expectancy is probably one of the best and most used measures we have for an objective quantification of health because it is a resultant of genetic and environmental factors of importance for life.

What is life expectancy?

Life expectancy is a statistical measure of the average time a person is expected to live, based on year of birth, current age, sex, and other demographic factors. The most commonly used measure is life expectancy at birth (LEB), which can be defined as the average number of years that a newborn is expected to live if current mortality rates continue to apply at a given year like 2020. 

Life expectancy over time

Thousands of years ago life expectancy at birth was about 25 years and it increased slowly until about 1870 when it was a marked increase in European life expectancy, and it has been a relatively linear increase all the way up to modern times from approximately 35 to 80 years. This means that we have had an amazing increase in life expectancy of more than three months per year for 150 years, as seen from the figure below. 

Geographical differences

It is also clear that there are marked differences in life expectancy between different geographical areas, ranging from about 35 years up to more than 82 years. Socio-economic inequalities - such as differences in education, financial situation, profession etc. - seem to be major factors for differences in life expectancy. From a global perspective, there is a high correlation between gross domestic product (GDP) per person and life expectancy, that is, high income is associated with a long life.
Another reason for different life expectancies between different countries is a different focus on prevention of infectious diseases caused by severe acute respiratory corona virus 2 (SARS-CoV-2) and human immunodeficiency virus (HIV). Infectious diseases have been a very important cause of premature death in human history.

Causes of increased life expectancy

Various genetic and environmental factors may potentially be important for alterations in life expectancy. 
Sanitary conditions like high quality drinking water and proper sewage  systems are essential to prevent infectious diseases, and a large fraction of the increase in life expectancy during the last 150 years can be ascribed to improved hygienic conditions. Moreover, improved care during pregnancy and delivery, and the neonatal period is very important because one life spared represents a whole lifetime. 
A balanced and healthy diet is also essential for a long life expectancy. It is important to reduce the risks of dietary deficiencies as well as accumulation of body fat due to overeating. 
Smoking represents a major environmental factor with very marked negative effects on health by enhancing risk of having cardio-vascular diseases, chronic obstructive lung syndrome, cancer in the lungs and several other organs, and osteoporosis. Every person and society with little use of tobacco will have positive effects on life expectancy.
Physical activity is highly variable among people, and it turns out to be very important for most organs in the body. In particular the risk of developing obesity and diabetes type 2 responds to physical activity.

Factors important for longevity are also factors important for good brain functions

Considering factors of importance for longevity, we notice a striking similarity to factors of importance for good brain functions as outlined in some previous E-newsletters. In another coming newsletter, we will specifically report on the effect of socio-economic status on brain structure and function.

Further reading:

• Timmers PRHJ et al.: Multivariate genomic scan implicates novel loci and haem metabolism in human ageing. Nature Communications. 2020, 11 (1), 3570
• Bloom DE, Canning D. Commentary: The Preston Curve 30 years on: still sparking fires. International Journal of Epidemiology. 2007, 36, 498–9, discussion 502–3. 
• Strand BH, Madsen C.: Social inequalities in health. Report of the Norwegian Institute of Public Health. 2018.
• Beard JR. et al. The World report on ageing and health: a policy framework for healthy ageing. Lancet, 2015, 387(10033), 2145–54
• World report on ageing and health. Geneva: World Health Organization; 2015, pp 1-260

Source of newsletter

This newsletter was edited by Christian A. Drevon, Lifebrain researcher. Professor emeritus of Medicine (nutrition) at the University of Oslo, and consultant in the analytical contract laboratory Vitas Ltd. in Oslo Science Park. Has studied effects of nutrients and physical activity on health, with special focus on molecular nutrition and biomarkers. 

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