Caloric restriction may influence aging by reducing telomere shortening.
- Animal studies suggest that restricting
calories may prolong life, and there is some evidence of a similar effect
in people, but experts do not yet understand exactly why.
- Telomeres are sections at the end of
chromosomes that shorten as cells age, and a new study has investigated
whether caloric restriction might slow this process and, therefore, the
rate of cell aging.
- In the study, people on restricted calories
lost more telomere length initially, but the shortening then slowed.
- The researchers plan to follow up participants
after 10 years to investigate whether prolonged caloric restriction slows
telomere shortening further.
It is well known that diet and exercise affect health,
and
It is this secondary aging that may be affected by
diet, and
Although several mechanisms have been proposed to
explain this effect, there is no firm evidence showing why caloric restriction
might prolong life.
Telomeres,
aging, and caloric restriction
As cells age,
Cell death is a feature of aging so, if cell death was
delayed by decreasing the rate at which telomeres shorten, might this delay
aging?
Now, researchers from Penn State University have
analyzed data from the Comprehensive Assessment of Long-term Effects of
Reducing Intake of Energy (
They
found that, initially, caloric restriction accelerated telomere shortening, but
after a year, it began to slow the process. At the end of 2 years, the calorie
restricted and control group had lost similar telomere length.
Their work appears in
Sebnem Unluisler, chief
longevity officer and genetic engineer at the London Regenerative Institute in
the United Kingdom, not involved in this research, told Medical News
Today:
“The study used a method to
track changes in telomere length over time with caloric restriction. Initially,
those eating less saw faster telomere shortening, but this slowed down later.
Surprisingly, after 2 years, both groups showed minimal difference, suggesting
a possible plateau effect. This highlights why long-term studies are vital to
understand aging-related processes fully.”
Restricting
calorie intake in healthy adults
The CALERIE trial
recruited 220 participants, of whom 175 were included in this data analysis.
All participants were aged between 21 and 50, healthy, and had a
Two-thirds of the participants committed to 25%
calorie restriction for 24 months, with the rest as controls who continued with
their normal diet.
The researchers advised all participants to undertake
moderate exercise for 30 minutes, at least 5 times a week, but not to alter
their activity levels during the course of the 2-year study. They provided
meals to those in the caloric restriction group for the first 27 days to help
them with food selection and portion size to ensure adequate intake of
essential nutrients throughout the study.
Over the
course of the study, the average calorie restriction fell short of the 25% aim,
with participants achieving a mean reduction of 11.9%.
At the start, and every 2 weeks throughout the study,
the researchers recorded the weight of all participants. During the first 12
months, those on caloric restriction lost weight, then their weight stabilized
over the next 12 months. Anyone whose BMI went below 18.5 (underweight)
discontinued the study.
Previous analyses of
the CALERIE data have shown that caloric restriction had some health benefits,
including reductions in total
Effect of
caloric restriction on telomeres
The researchers measured
telomere length from blood samples taken at the start of the study, at 12
months, and at 24 months.
They
found that in the first 12 months, telomere length decreased faster in people
on caloric restriction. In the second year, the rate of decrease slowed to a
lower rate than that of control subjects.
The researchers explained why this might have
happened:
“[T]he stress of weight loss that accompanies early-phase
CR [caloric restriction] accelerates TL [telomere] attrition, which is
thereafter mitigated or ablated altogether as new homeostatic norms are
established,” they wrote.
Unluisler suggested that: “Eating less could reduce
stress and inflammation in the body, slowing down telomere shortening. It might
also help cells repair themselves better.”
Over the
2-year study, there was no significant difference in telomere length change
between the 2 groups.
A key to
healthier aging?
Idan Shalev,
PhD, associate professor of biobehavioral health at Penn State, who
led the research, said that the 2-year study was not long enough to draw firm
conclusions about the effect of caloric restriction on telomere length.
“This research shows the complexity of how caloric
restriction affects telomere loss,” he said in a press release. “We
hypothesized that telomere loss would be slower among people on caloric
restriction. Instead, we found that people on caloric restriction lost
telomeres more rapidly at first and then more slowly after their weight stabilized.”
The team will follow up the cohort at 10 years to see
what happens to telomere length over this longer time period.
Unluisler told MNT that telomere dynamics was probably just one
factor in aging: “This study adds valuable insights into how diet affects
cellular aging. It emphasizes the complex relationship between genes, the
environment, and lifestyle choices in shaping health outcomes.”
“Future research should combine different fields to
create personalized approaches for healthy aging and disease prevention,” she
added.
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