April 19, 2017 -- Do tiny pieces of DNA hold the secret to aging?
Called telomeres, these tips on the ends of our chromosomes are generating heated debate as scientists try to better understand their role in aging.
A book released earlier this year titled The Telomere Effect: A Revolutionary Approach to Living Younger, Healthier, Longer says our lifestyle choices affect our telomeres and how we age.
Nobel Prize winner Elizabeth Blackburn, PhD, and University of California San Francisco health psychologist Elissa Epel, PhD, wrote the book, which made the New York Times best-seller list.
“The foods you eat, your response to emotional challenges, the amount of exercise you get, whether you were exposed to childhood stress, and even the level of trust and safety in your neighborhood -- all of these factors and more appear to influence your telomeres and can prevent premature aging at the cellular level,” the authors write.
But some doctors and scientists argue the book is oversimplifying the science. And it comes at a time when researchers are questioning what role telomeres play in the aging process.
“There is no question that telomeres are part of the story,” says S. Jay Olshansky, PhD, of the University of Illinois, Chicago. “Are they the magic bullet that will allow us to live much longer? That’s the missing part of the equation that nobody can provide.”
So what exactly are telomeres?
Much like plastic ends on shoelaces, telomeres protect the ends of our chromosomes that carry our DNA, or genetic material.
Telomeres wear down and get shorter over your lifetime, harming their ability to protect chromosomes. When this happens, new cells don’t replace old ones. Researchers have been studying whether this cellular aging is a root cause for diseases and other problems that happen as we get older.
In 2009, Blackburn was part of a team that won the Nobel Prize in Physiology for discovering that an enzyme called telomerase can help lengthen your telomeres.
Blackburn’s book delves further into the research around telomeres and what may affect them. In it, the co-authors make the case that while telomeres are just one pathway of aging, certain lifestyle changes might stabilize telomeres or increase telomerase and help prevent aging. The book says many studies show those lifestyle behaviors include diet, exercise, sleep, and actions related to chronic stress and mental well-being.
Among them:
- A small study found 45 minutes of moderate exercise, three times a week for six months “increased telomerase activity twofold.”
- A 2012 study found that sleeping fewer hours was associated with shorter telomere length in healthy men.
- Other studies show a Mediterranean diet is associated with longer telomeres.
“Small things we do each day add up in their effect over years and years,” Epel says. “If we are on a path for a long health span, we are not wearing our cells out, but rather getting the right nutrition and antioxidants, some activity, some joy and satisfaction, and enough restorative sleep each night, so the telomeres are maintained over years and years.”
Epel says scientists don’t know how easily we can change our telomere length and whether changing it in the short term makes much of a difference for longevity. That’s in part because long-term studies haven’t been done.
“There are indeed no single studies that have shown that lifestyle can change telomeres and in turn longer telomeres can lengthen life span,” Epel says. “But as with any behavior, the longer we do it, the more we maintain the benefit.”
Other experts say that except for a few diseases, like pulmonary fibrosis, most telomere research at this point shows only associations rather than direct cause and effect.
“We don’t understand how telomeres affect aging," says Titia de Lange, PhD, a professor and head of the Laboratory of Cell Biology and Genetics at The Rockefeller University in New York. She’s studied telomere for 3 decades.
“Telomeres get shorter with age but this is all correlative, so it could be like grey hair: Yes, it happens but it’s not going to kill you,” de Lange says. “Basically none of the big questions have been answered. There is just a lot of correlative data -- some with dubious validity -- that so far has raised more questions than given answers.”
Mary Armanios, MD, clinical director of the Telomere Center at Johns Hopkins Hospital in Baltimore, says the research community has more nuanced views about telomeres.
“It is not so simple that short telomeres are bad and long telomeres are good. What we are finding is that ‘middle-of-the-road’ telomeres are the best. There is also growing evidence that telomeres cannot be altered by environmental choices,” she says.
Armanios outlined this side of the research in a 2015 review that explained that longer telomeres also have a dark side: They are associated with the risk of several cancers. Like regular cells, cancer cells have telomeres.
She says that telomeres became a pop culture phenomenon because we can measure them. “The fact that they are measureable in contrast to other changes with aging has put them in the spotlight,” Armanios says.
But aging is complicated, and many things, including our genes and environment, contribute to how we age, she says. “A telomere-centered view is a very narrow way to look at human aging in general, and the picture is more complicated.”
Olshansky says the telomere story has “fallen flat” in our understanding of aging.
“Researchers believed for a while that this was going to be a magic bullet -- that if you could stop cells from losing telomeres the organisms could become immortal,” says Olshansky, a member of the board of directors of the American Federation of Aging Research. “It doesn’t mean there isn’t something to be learned here, but overall the aging process is not driven by telomeres shortening.”
So how should you approach aging? While many researchers debate the role of telomeres in aging, they agree on the benefits of a healthy lifestyle.
“There is ample evidence that lifestyle factors can mitigate the complex factors that lead to aging in general,” Armanios says. “Diet, exercise, stress reduction, enough sleep -- these things are good for all of us even though evidence that they lengthen telomeres is not clear in my mind.”
“The only equivalent of a fountain of youth that exists is exercise and diet and avoiding harmful behavior and risk factors like smoking and obesity,” Olshansky says. “If you are doing this, you are doing as much as you can to allow your genetic potential to play out.”