Studying extends the lifespan of non-smokers

For every year spent studying at university, lifespan is extended by one year. But, if you smoke, this advantage is immediately lost. This is what scientists involved in the SystemsX.ch research initiative have discovered.

Scientists at the University Hospital of Lausanne (CHUV) and at the SIB Swiss Institute of Bioinformatics, as part of a SystemsX.ch research project, have discovered the recipe for a long life. They compared the genes, lifestyles and life expectancies of 600,000 people. As a result, they managed to identify one of the most decisive factors in prolonging life expectancy: how much time someone has spent studying at university. The statistics show that life expectancy increases by one year for every year spent studying.

“A person’s level of education is indicative of their social and financial status. Educated and wealthy people have better access to sports facilities, are more health-conscious and go more often to the doctor’s. In addition, they generally have better access to health care, for example through private health insurance,” says the leader of the study Zoltán Kutalik, a biostatistician at the CHUV and Group Leader at SIB. However, the formula only works up to PhD level. The study data did not elucidate whether those who continue studying beyond this point prolong their lives even further. And certainly, professors don’t live forever.

7 years for giving up smoking
Kutalik and colleagues also examined the effect smoking has on longevity. Their results show that a packet of cigarettes a day shortens someone’s life by seven years. The good news is, those who stop smoking at some point live almost as long as those who have never smoked. That means, whoever stops smoking gives themselves another 7 years of life.

Overweight: 2 months per kilo
Being overweight has less of an influence on life expectancy. For every kilogram of weight you lose, your life is lengthened by only two months. So if you reduce your weight from 90 to 80 kilograms, you’d get back just over a year and a half. However, this correlation only applies to someone with a body mass index (BMI) between 23 and 28 (one is classified as overweight with a BMI over 25). “We suspect that the number of years of life lost per extra kilo decreases, the more overweight one is,” says Kutalik. In other words, the consequence on lifespan of being 120 kg versus 130 kg is less pronounced than the difference between being 70 kg versus 80 kg.

Lifestyle is more important than genes
The researchers have also identified two new genes that play a role in life expectancy. The first, with the complicated name HLA-DQA1/DRB1, helps the immune system fight threats such as bacteria or viruses. Those who possess a specific version this gene will live on average half a year longer.

The second gene is responsible for cholesterol levels in the blood. It has a genetic marker that comes in two versions: one increases the cholesterol level, and the other lowers it. Those carrying the latter will live on average eight months longer.

Altogether there are around 20 genes currently known to have an influence on life expectancy and many more yet to be discovered. The DNA code explains only a quarter of the variation between individuals’ lifespan. The other three quarters are accounted for by lifestyle factors, such as level of education, smoking, obesity and other environmental factors.

Further reading:
Peter K. Joshi et al. (2017) Genome-wide meta-analysis associates HLA-DQA1/DRB1 and LPA and lifestyle factors with human longevity. Nature Communications. DOI:10.1038/s41467-017-00934-5

Contact
Zoltán Kutalik, University Hospital of Lausanne (CHUV)/University of Lausanne / SIB Swiss Institute of Bioinformatics, +41 21 314 67 50, zoltan.kutalik(at)unil.ch