A study published last week in the journal Nature aims to consolidate our understanding of which genetic and lifestyle factors have a significant impact on how long we can expect to live.
The research — conducted by scientists from the University of Edinburgh in the United Kingdom — analyzed data sourced from as many as 25 different population studies, spanning three continents. These were Europe, Australasia, and North America.
“The power of big data and genetics allow us to compare the effect of different behaviors and diseases in terms of months and years of life lost or gained, and to distinguish between mere association and causal effect,” explains study co-author Prof. James Wilson.
Two genetic variations impact lifespan
For the purpose of this study, the researchers looked at data collected from 606,059 people. They studied the participants’ genetic makeup, also taking into consideration the lifespan of their parents.
First, the researchers noted that variations of two genetic regions can influence our lifespan. A variation of the HLA-DQA1/DRB1 genetic region, which is tied to the functioning of the immune system, could add approximately 6 months to our lifespan.
At the same time, a variation of the LPA genetic stretch — which is implicated in the regulation of blood cholesterol — can take approximately 8 months off of our expected lifespan.
In their paper, the researchers say that this is the first time that the role of these genetic variations in the context of life expectancy has been confirmed.
Other genetic traits, which predispose us to different types of addiction or to various diseases, are also to blame for a reduced life expectancy.
Top influencers: Smoking, weight, education
One of the most “dangerous” genetic predispositions, the scientists explain, is the one that dictates an inclination toward nicotine dependence, which can lead to lung cancer and other pulmonary diseases.
A deep-seated habit of smoking a pack of 20 cigarettes each day reduces lifespan by around 6.8 years, the researchers found.
However, they also said that giving up smoking could reverse this effect, and allow former smokers to enjoy a longer lifespan.
Excess weight is also a major factor, as each extra kilo was found to reduce life expectancy by 7 months.
“We found that, on average, smoking a pack a day reduces lifespan by 7 years, while losing 1 kilogram of weight will increase your lifespan by 2 months.”
Study co-author Dr. Peter Joshi
Other interesting — and perhaps surprising — findings of the study were tied to the impact of education, especially that of pursuing learning beyond the compulsory school years.
Education, the researchers noted, is responsible for 11 extra months added to the lifespan for each year spent studying on top of the normally required school training.
The study was designed to eliminate confounding variables as much as possible, so that causal, rather than correlational, relationships between genetic makeup, lifestyle choices, and life expectancy could be clearly established.