A new study seeks to answer a long-standing question: which has a greater influence on longevity: genetics or lifestyle? Bradley Elliott explains.
As people who study aging often say, the best thing you can do to extend your life is to choose good parents.
After all, it has long been recognized that people who live longer tend to have longer-lived parents and grandparents, suggesting that genetics influences longevity.
However, complicating the situation is that lifestyle, especially the sum of diet and exercise, is also known to have a significant impact on health and longevity in later life. How lifestyle and genetics play a role is an open question, but a recent study published in the journal Nature has shed new light.
Scientists have long known that animals can live longer if they reduce their caloric intake. In the 1930s, it was noted that rats that ate reduced calories lived longer than rats that ate as much as they wanted. Similarly, physically active people tend to live longer. However, linking a single gene specifically to longevity has been controversial until recently.
Cynthia Kenyon, who was studying the lifespan of tiny worms, Caenorhabditis elegans, at the University of California, San Francisco, discovered that small changes to genes that control how cells detect and respond to nutrients in their surroundings can shorten the lifespan of worms. I discovered that this led to doubling the amount.
This raises new questions. If we know that genetics and lifestyle influence lifespan, which is more important? And how do they interact?
A new study published in the journal Nature examined various models of calorie restriction in 960 mice to tease out the effects of genetics and lifestyle. Researchers specifically found that calorie restriction (eating 20% or 40% fewer calories than control mice) or intermittent fasting, which consists of 1 to 2 days of no food (intermittent fasting, may have positive health effects) We focused on the classic experimental model (because it is popular among those seeking it). calorie restriction).
The researchers specifically used genetically diverse mice because small genetic variations are known to affect aging. This is important for two reasons. First, laboratory studies in mice are typically conducted on genetically very similar mice, which allows researchers to uncover the effects of both diet and genetic variables on longevity. I did.
Second, humans are so diverse that studies on genetically nearly identical mice are unlikely to lead to high genetic diversity in the human race.
The headline finding was that genetics appears to play a larger role in longevity than dietary interventions. The long-lived mice still lived longer despite the change in diet.
Diet is important, but genes are even more important.
And although short-lived mice showed improvement as a result of dietary restriction, they were unable to catch up with long-lived mice. This suggests that the joke about “choosing good parents” is true.
The caloric restriction model still extended lifespan in all mouse types, with the 40% restriction group having increased mean and maximum lifespans compared to the 20% group.
And 20% of the groups showed improvements in both the group’s average lifespan and maximum lifespan compared to the control group. The effect of genetics was simply greater than the effect of dietary intervention.
All caloric restriction models extended the lifespan of mice on average, but in the most extreme caloric restriction model tested (40% less group) changes that would be considered physical harm were observed. These include decreased immune function and reduced muscle mass, which can impact health and longevity outside of a predator- and bacteria-free laboratory environment.
There are some important caveats to such studies. First, it is unclear whether these results apply to humans.
As with most calorie restriction studies in mice, the feeding restriction groups were given either 20% or 40% less food than the control group, who ate as much as they wanted. In human terms, it’s like believing that eating from a bottomless buffet every day is “normal.” And a person who does not eat from an endless tray of food is a “restriction feeder.” It’s not exactly the same as how humans live and eat.
Second, although exercise was not controlled at all in this study, most groups completed similar amounts of running on a caged wheel, with the exception of the 40% caloric restriction group, which ran significantly more. went.
The researchers suggested that this extra exercise in the 40% group might be due to the mice constantly hunting for more food. However, this group exercised much more than the other groups, which may mean that this group also saw the positive effects of increased exercise along with calorie restriction.
Therefore, although we cannot choose our parents or change the genes we inherit from them, we do know that certain genetic variations play an important role in the maximum age we can aspire to. Interesting to know.
The genetic cards we are dealt determine how long we will live. But just as important as this study, lifestyle interventions such as diet and exercise aimed at extending lifespan should be effective regardless of the genes we carry.
– Bradley Elliott is Senior Lecturer in Physiology at the University of Westminster.
This article is republished from The Conversation under a Creative Commons license.
