In animals, it had already been proven that restricting calorie intake delays aging, but a group of researchers from the Mailman School of Public Health at Columbia University (USA) has carried out a study with 220 healthy adults not obese – the phase 2 CALERIE™ randomized controlled trial – which has shown that caloric restriction also slows the rate of biological aging in humans.
Study participants were randomly selected at three sites in the United States and underwent 25% caloric restriction or followed a normal diet for two years. The dietary intervention achieved a 2 to 3% reduction in the rate of aging, which in other investigations constitutes a 10 to 15% decrease in the risk of mortality, an impact similar to that of quitting smoking.
“In worms, flies, and mice, caloric restriction can slow the biological processes of aging and prolong healthy life,” said Daniel Belsky, Mailman associate professor of epidemiology and lead author. “Our study aimed to test whether caloric restriction also delays biological aging in humans.” The findings have been published in Nature Aging.
Measurement of the rate of aging or the rate of biological deterioration
CALERIE™ is an acronym for ‘Comprehensive Assessment of the Long-Term Effects of Reducing Energy Intake’, it has been funded by the US National Institute on Aging which is part of the National Institutes of Health and it is the first investigation into the effects of long-term caloric restriction in healthy, non-obese humans. The rate of aging was measured from the methylation of the participants’ blood DNA using the DunedinPACE (Pace of Aging, Computed from the Epigenome) algorithm.
The investigators collected and analyzed blood samples from the participants before the intervention and at 12- and 24-month follow-up. Belsky has explained that due to the longevity of human beings it is not practical to follow them until they observe the differences in the diseases associated with aging or survival and that for this reason they used “biomarkers developed to measure the rate and progress of biological aging at throughout the study”.
“Our findings are important because they provide evidence from a randomized trial that it is possible to delay human aging”
So they looked at DNA extracted from white blood cells for methylation marks, which are chemical tags in the DNA sequence that regulate gene expression and are known to change during the aging process. They initially focused on three measurements of DNA methylation data, also known as “epigenetic clocks.”
The first two measurements based on the PhenoAge and GrimAge clocks estimate biological age, or the chronological age at which a person’s biology would appear “normal.” These measurements can be thought of as “odometers” that provide a static measure of the aging a person has experienced. The third measure they studied was DunedinPACE, which estimates the rate of aging, or rate of biological decline over time, and can be thought of as a “speedometer.”
The results showed that “caloric restriction slows the rate of aging in humans,” said Calen Ryan, a research scientist at Columbia’s Butler Aging Center and co-senior author of the Ryan study. “But caloric restriction probably isn’t for everyone. Our findings are important because they provide evidence from a randomized trial that delaying human aging is possible. They also give us an idea of the types of effects we might look for in trials of interventions that might appeal to more people, such as intermittent fasting or time-restricted eating,” she adds.
Other research has associated the slower DunedinPACE measure with decreased risk of cardiovascular disease, disability, and dementia. Researchers are currently following the people who participated in the trial to find out if the intervention has long-term effects on healthy aging, such as a decrease in chronic diseases associated with aging or their risk factors.
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