Researchers at the University of Zurich documented for the first time the impact of behavioural factors on life expectancy in numbers.
The incidence of non-communicable diseases (NCDs) such as cardiovascular diseases (CVDs), cancer, diabetes and chronic respiratory disorders is constantly rising in industrialised countries, researchers said.
Attention is focusing, amongst other things, on the main risk factors for these diseases which are linked to personal behaviour - ie tobacco smoking, an unhealthy diet, physical inactivity and harmful alcohol consumption.
Brian Martin and his colleagues from the Institute of Social and Preventive Medicine (ISPM) at Zurich have examined the effects of these four factors - both individual and combined - on life expectancy.
For the first time the consequences of an unhealthy lifestyle can be depicted in numbers. An individual who smokes, drinks a lot, is physically inactive and has an unhealthy diet has 2.5 fold higher mortality risk in epidemiological terms than an individual who looks after his health.
"A healthy lifestyle can help you stay ten years' younger," said lead author Eva Martin-Diener.
For the study the researchers used data from the Swiss National Cohort (SNC).
The Zurich public health physicians focused on CVDs and cancer as they account for the most deaths in Switzerland.
The researchers succeeded in correlating data on tobacco consumption, fruit consumption, physical activity and alcohol consumption from 16,721 participants aged between 16 and 90 from 1977 to 1993 with the corresponding deaths up to 2008.
"The effect of each individual factor on life expectancy is relatively high," said Martin-Diener. But smoking seems to be the most harmful.
Compared with a group of non-smokers, smokers have a 57 per cent higher risk of dying prematurely. The impact of an unhealthy diet, not enough sport and alcohol abuse results in an elevated mortality risk of around 15 per cent for each factor, researchers said.
"We were very surprised by the 2.5 fold higher risk when all four risk factors are combined," said Martin.
Hence, the probability of a 75-year-old man with all risk factors surviving the next ten years is, for instance, 35 per cent, without risk factors 67 per cent - for a woman 47 and 74 per cent respectively.