The study is based on an analysis of information from almost 500,000 participants in the UK BioBank database, including responses to questionnaires as well as data on deaths and illnesses that occurred after people were enrolled.
The study suggests that environment is about 10 times more important than genes in explaining why some people have a higher risk of early death than others, the Guardian reported.
The study was based on an analysis of information from nearly 500,000 participants in the UK's BioBank database, including responses to questionnaires as well as data on deaths and illnesses that occurred after people enrolled.
Experts say the work highlights the importance of "exposure" - the many environmental factors we encounter in our lifetime, from living conditions to whether we smoke - to health, including how we age and why we develop age-related chronic diseases.
Dr Austin Argentieri, first author of the Harvard and Broad Institute study, said:
"Investment in understanding and changing the environment is likely to have a major impact on improving the health of us all."
In the journal Nature Medicine, Argentieri and his colleagues at Oxford and other institutions report how they analysed whether 164 environmental factors - from salt intake to living with a partner - were associated with the risk of premature death.
After ruling out, for example, factors related to existing diseases or those that might simply reflect another underlying factor, the team was left with 85 environmental exposures associated with the risk of premature death.
They then carried out further analysis based on proteins in the blood to identify which of these exposures were also linked to how quickly people age biologically.
The resulting 25 environmental exposures included childhood factors, such as maternal smoking around birth and whether participants were relatively low at age 10, as well as more recent factors, such as whether participants were employed and their household income.
Alcohol intake and other aspects of diet were not among the exposures, possibly, according to the researchers, because of the difficulty of examining these factors through questionnaires and inconsistencies in their associations.
The team reported that many of the 25 exposures showed associations with certain age-related diseases and biomarkers of aging. This, according to Argentieri, sheds light on the different ways in which they may affect early mortality. Importantly, 23 of these exposures can be modified.
In further analysis, the team found that age and sex together explained about half of the variation in risk of premature death, while the 25 environmental exposures together explained another 17% of the variation. In contrast, genetic susceptibility to 22 major diseases explained less than 2% of the additional variation.
Environmental exposures are also more important than genes in explaining why some people are at higher risk of developing lung, heart and liver disease in the future.
However, the opposite is true for diseases such as breast cancer, prostate cancer and dementia, indicating that in some cases genetic risk is more important.
Argentieri said:
"We provide some of the first evidence from a well-designed study to outline all the exposures that affect ageing at a biological level. Furthermore, we show that these exposures are likely linked to the entire aging process in adulthood as they relate to key biological mechanisms of aging, future risk of age-related disease and mortality."
The study has limitations, including that the results may differ in other countries, environmental exposures were measured at only one point in time, the associations raised reflect cause and effect, and there may be environmental exposures that were not taken into account. | BGNES