New study tries to unpick which has a greater impact on lifespan

As aging researchers often joke, 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.

But what complicates the situation is the sum of your lifestyle, specifically diet and exerciseit also has a significant impact on health and life expectancy even in old age. What influence lifestyle and genetics have is an open question. recent research in nature shed new light on it.

Scientists have long known that reducing caloric intake can help animals live longer. in 1930sIt was noted that rats fed a diet with reduced calories lived longer than those who ate as much as they wanted. Similarly, physically active people tend to live longer. However, linking a single gene specifically to longevity was controversial until recently.

While studying the lifespan of the tiny nematode C. elegans at the University of California, San Francisco, Cynthia Kenyon They found that small changes to genes that control how cells detect and respond to surrounding nutrients led to doubling the worm’s lifespan. This raises new questions. If we know that genetics and lifestyle influence lifespan, which is more important? And how do they interact?

The following new study was conducted to try to uncover the influence of genetics and lifestyle. nature investigated various models of caloric restriction in 960 mice. Researchers are particularly interested in calorie restriction (eating 20% ​​or 40% fewer calories than control mice) or intermittent fasting, which consists of 1-2 days of no food (intermittent fasting is a method of seeking positive health effects). We focused on the classic experimental model (because of its popularity among people). calorie restriction).

The researchers used particularly genetically diverse mice because we now know that small genetic variations can 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.

Short-lived mice showed improvement as a result of dietary restriction, but this did not 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 types of mice, with the 40% restriction group having increased mean and maximum lifespans compared to the 20% group.

The 20% group showed an improvement in both mean lifespan and maximum lifespan of the group compared to the control group, but the influence of genetics was greater than the effect of the dietary intervention.

All caloric restriction models increased the lifespan of mice on average, but in the most extreme caloric restriction model tested (<40% 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 it’s “normal” for people to eat from a bottomless buffet every day, and that anyone who doesn’t eat from an endless tray of food is practicing a “restrictive diet.” 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 performed a similar amount of running on a wheel in their cages, except for the 40% calorie-restricted group, which ran significantly more. .

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.

So while we can’t choose our parents or change the genes we inherit from them, it’s important to know that certain genetic variations play an important role in the maximum age we can aspire to. That’s interesting.

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.

This article is republished from conversation Under Creative Commons License. please read original article.