Lifestyle changes that bring to mind David Carradine's "grasshopper" character in the cult 1970s TV series Kung Fu have the power to reverse ageing at a fundamental level, evidence suggests.
A pilot study comparing two groups of cancer patients found a genetic effect on cells that protects against diseases of ageing and premature death.
Its authors believe their findings have far-reaching implications for everyone, not just cancer sufferers.
The research focused on telomeres - caps on the ends of chromosomes, the twisted strands of DNA housing our genes - that have a similar function to the plastic tips of shoelaces.
Just as shoelace tips stop fraying, telomeres keep chromosomes stable and prevent mix-ups when cells divide.
Telomeres shorten as we age and shorter telomeres have been associated with a greater risk of early death and age-related conditions such as heart disease, dementia, diabetes, cancers and vulnerability to infection.
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The scientists looked at two small groups of men with early non-aggressive prostate cancer who had not undergone surgery or radiotherapy but were having regular "active surveillance" condition checks.
One group of 25 men continued life as normal without making any changes.
Ten other participants underwent a radical lifestyle transformation, supervised by doctors, nutritionists and psychologists.
Their diet was switched to one high in plant-based proteins, fruits, vegetables and unrefined grains, and low in fat and processed carbohydrates, and they were taught de-stressing techniques such as yoga and meditation.
They also engaged in moderate levels of exercise, such as walking for 30 minutes six days a week, and were given social support including counselling.
After five years, blood tests showed that the telomeres of the healthy lifestyle group had lengthened significantly by an average of 10%.
Those of the "no change" control group decreased in length by an average of 3% over the same period of time.
But members of the control group who chose to adopt a healthier lifestyle were also able to maintain longer telomeres.
The study, reported in the journal The Lancet Oncology, found no significant difference between the groups in levels of PSA, the blood marker used to monitor the progress of prostate cancer.
Nevertheless, the scientists believe their findings carry an important health message.
Professor Dean Ornish, from the Preventive Medicine Research Institute at the University of California in San Francisco, US, who led the team, said: "The implications of this relatively small pilot study may go beyond men with prostate cancer.
"If validated by large-scale randomised controlled trials, these comprehensive lifestyle changes may significantly reduce the risk of a wide variety of diseases and premature mortality.
"Our genes, and our telomeres, are a predisposition, but they are not necessarily our fate."
It is well known that each time a cell divides, its telomeres shorten. In the end they can no longer ensure chromosomal stability and genetic mistakes start to occur.
Eventually the cell freezes and stops dividing, a state known as senecense, or destroys itself.
The speed at which telomeres shorten varies in individuals and biological ageing is faster in people with rapidly-shortening telomeres.
Short telomere length in white blood cells is especially associated with age-related diseases, including many types of cancer.
It has been suggested as a trigger mechanism for the genetic scrambling associated with prostate cancer. Men with short telomeres in prostate cancer-associated cells are much more likely to die from the disease.
Previous research has linked a number of non-genetic factors with altered telomere length, the scientists pointed out. One of these is chronic or severe psychological stress, which has been shown to accelerate biological ageing.
Emotional stress in mothers has been correlated with short telomere length in white blood cells.
In the new study, the researchers found that higher levels of stress hormones such as cortisol and adrenalin were associated with shorter white blood cell telomeres.
The research is the first to indicate that lifestyle changes can have a beneficial impact on telomeres over a long period of time.
Earlier work by the same team showed that a three-month meditation retreat significantly increased activity of an enzyme that helps to maintain telomere length.
The scientists wrote: "In conclusion, our comprehensive lifestyle intervention was associated with significant increases in relative telomere length in men with early-stage prostate cancer, compared with active surveillance alone.
"Adherence to these healthy behaviours was also associated with increased relative telomere length when all study participants were assessed together.
"These results add to existing data and suggest that further investigation in randomised trials in larger and different populations would be useful."
Biochemist Dr Lynne Cox, from Oxford University, said: "The association between short telomeres, stress and poor health is well documented in the literature. This new study suggests that reducing stress, improving diet and increasing exercise have the effect of not only preventing telomere loss but also of leading to small but significant increases in telomere length, as measured in circulating white blood cells.
"The greater the adherence to the healthy lifestyle changes, the greater the increase in telomere length measured; it is perhaps too soon to judge whether this increase in telomere length will correlate with increased longevity or healthspan.
"There are two things to bear in mind here. Firstly, short telomeres that occur as result of chronic stress are highly associated with poor health, and studies in mice have shown improved tissue health when telomeres are restored experimentally.
Secondly, by contrast, globally increasing telomere length in cancer-prone mice actually predisposes to more aggressive cancers.
"The small increases in telomere length in this new human study are more likely to correlate with improved health than cancer risk, though it is too early to be definite."
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