Sit Less, Protect Your DNA and Live Longer?

Finding may help explain why sitting a lot has been linked to poor health

By Steven Reinberg
HealthDay Reporter

WEDNESDAY, Sept. 3, 2014 (HealthDay News) -- Spending less time sitting might increase your lifespan by keeping your DNA young, Swedish researchers say.

More time spent on your feet appears to lengthen bits of DNA called telomeres. Telomeres, which protect the end of chromosomes (like the tips that keep shoelaces from fraying), tend to get shorter and shorter until they can't shorten any more, causing cells to die.

"Our data indicate that lengthening of our telomeres may be one mechanism that induces health benefits after lowering sitting time in elderly people," said lead researcher Per Sjogren, an associate professor in the department of public health and caring sciences at Uppsala University.

"One should, of course, be careful with the conclusions, since our study is rather small and needs to be confirmed in larger trials," Sjogren said.

However, this is the first study describing a possible relationship between physical activity and lengthening of telomeres, according to Sjogren.

"Telomeres have attracted a lot of interest in the last few years because they are situated at the end of our chromosomes and have shown to be important for DNA replication and cell survival. The interest of whether telomeres may affect health and longevity has increased," Sjogren said.

Telomeres stop chromosomes from fraying or clumping together and scrambling the genetic codes they contain, the researchers noted.

Why spending less time sitting might lengthen telomeres isn't known. "That is a valid question that remains to be resolved," Sjogren said.

Dr. David Katz, director of the Yale University Prevention Research Center, said, "There has long been evidence that the more hours we spend sitting every day, the fewer days we are likely to have to spend sitting, or doing anything else for that matter. Hours per day on our backsides correlate with reductions in life expectancy."

There has also long been evidence that healthy living, including routine activity, can add years to life, he said.

Compelling evidence has already shown that lifestyle changes can alter genes and affect telomere length, said Katz, who was not involved with the study.

"This study adds a missing snippet to that tale by noting a direct correlation between reduced time sitting each day and increased telomere length," he said.

"Long telomeres are good -- long hours sitting, not so much," Katz added.

For the study, researchers analyzed the length of telomeres in the blood cells of 49 sedentary and overweight people in their late 60s. Blood samples were taken two times, six months apart.

All of the participants took part in an earlier study where they were randomly assigned to an exercise program or asked to keep their usual routine.

Although the exercise intervention wasn't linked to longer telomeres, less time sitting was associated with increased telomere length, the researchers found.

The report was published online Sept. 3 in the British Journal of Sports Medicine.

More information

For more about healthy aging, visit the U.S. Centers for Disease Control and Prevention (http://www.cdc.gov/aging/ ).

SOURCES: Per Sjogren, Ph.D., associate professor, department of public health and caring sciences, Uppsala University, Uppsala, Sweden; David Katz, M.D., M.P.H., director, Yale University Prevention Research Center, New Haven, Conn.; Sept. 3, 2014, British Journal of Sports Medicine, online

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