Exercise, a healthy diet and good sleep can protect the body against the negative effects of stress and slow down the aging process at a cellular level, researchers report.
A study involving hundreds of older women found that stressful events are linked to increased shortening of telomeres, the protective caps at the ends of chromosomes that affect how quickly cells age.
"We found that over a one-year period, the more stressors a woman had, the more their telomeres were likely to shorten," said lead author Eli Puterman, assistant professor of psychiatry at the University of California, San Francisco School of Medicine.
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But women who maintained active lifestyles, ate right and slept well appeared to shrug off the effects of stress, with their telomeres showing no significant additional shortening, the researchers said.
Dr. Michael Speicher, professor and chairman of the Institute of Human Genetics at the Medical University of Graz in Austria, said the study "addresses a really important biological question: why a healthy lifestyle is really helpful, especially if you are exposed to stressors."
"The hopeful message is if you engage in these healthy behaviors, you can decrease some effects that stress can have on your body," he said.
Telomeres are like the plastic tips on the ends of shoelaces that keep the laces from unraveling.
Composed of DNA and protein, they protect the ends of chromosomes and keep them from unraveling. As telomeres become shorter and their structural integrity weakens, cells age and die faster.
This sort of cellular aging has been associated with age-related illnesses such as cardiovascular disease, Alzheimer's disease and cancer. One theory holds older people are more prone to develop cancer because their shortened telomeres have made their chromosomes unstable and likely to malfunction, said Speicher, who wasn't involved in the new study.
Telomeres naturally grow shorter with age, but unhealthy behaviors such as smoking, poor diet and too little sleep can cause them to shorten sooner, Puterman said. Chronic emotional stress also has been linked to shorter telomeres.
To see whether a healthy lifestyle can combat the effects of stress, researchers followed 239 post-menopausal, nonsmoking women for one year. The findings are published July 29 in the journal Molecular Psychiatry.
The women provided blood samples at the beginning and the end of the year for telomere measurement. They underwent periodic reviews of their physical activity, diet and sleep.
At the end, the women also reported on stressful events that occurred during the year. Researchers focused on truly stressful life events, such as becoming a caregiver to a sick relative, losing a house or a job, or having someone dear to them die, Puterman said.
The researchers found that these major stress events caused a significantly greater decline in telomere lengths for women who halfheartedly engaged in healthy behaviors.
But the same levels of stress caused no greater shortening in the telomeres of women who stayed active, ate healthily and slept well.
The study shows the importance of maintaining a healthy lifestyle during challenging periods in your life, Puterman and Speicher said.
"If we are in stressful situations, physical activity, sleep and nutrition are of really great importance to keep our bodies in shape and stay healthy," Speicher said. "With this study we see it on the genetic level now."
The study also adds to our understanding of how healthy living affects the aging process, Puterman said.
"The same type of person who eats well and still exercises is the same sort of person who isn't aging much," he said. "As we get deeper and deeper into the cell, we're getting more information about why and what's happening at the genetic level."
The study doesn't actually prove a cause-and-effect relationship between healthy habits and longer telomeres, however. The next step will be randomized trials to see whether exercise can be used to slow cellular aging for people facing ongoing life stress, such as those serving as caregivers to Alzheimer's patients.
"We're going to look to see whether we can shift their aging processes within their cells, as well as depression levels and stress levels and that sort of thing," Puterman said.
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Although the study was limited to women, both experts said it would make sense that the findings would apply to men.
Speicher went further: "There are several studies out there claiming men on average have shorter telomeres than women," he said. "One could suppose that the effects on men would be even greater than on women, but that's just a theory."