Penn State researchers have discovered that the rate at which human cells age can be affected by a variety of interconnected factors. In a recent study, they looked into how restricting calories can impact telomere length and biological aging. The study, led by researchers in the Penn State College of Health and Human Development, focused on how caloric restriction affects a person’s telomeres, which are genetic bases that act as protective caps at the ends of chromosomes. The team’s findings were published in a journal.The researchers found that in a two-year study of caloric restriction in humans, those who restricted their calories lost telomeres at different rates compared to the control group, even though both groups ended the study with similar telomere lengths. Previous research has shown that restricting calories by 20% to 60% can promote longer life in many animals. As people’s cells replicate over their lifetime, telomeres are lost when chromosomes are copied to the new cell, causing the overall length of the cell’s telomeres to become shorter.Cells divide and replicate a certain number of times, until the protective cap of telomeres is completely depleted. At this point, the genetic material in the chromosome can become damaged, leading to potential issues with cell reproduction and function. Interestingly, a cell with longer telomeres is considered biologically younger than a cell with shorter telomeres, which means that two individuals of the same age could have different biological ages based on the length of their telomeres. Various factors such as aging, stress, illness, genetics, and diet can all impact the rate of cell replication and the length of telomeres, as explained by Idan Shalev, an associate professor of biobehavior.Shalev, a researcher at Penn State, led a study analyzing genetic samples from the CALERIE study. This study was the first of its kind to explore the effects of calorie restriction in humans through a randomized clinical trial. The focus of Shalev’s research was to investigate how caloric restriction affects telomere length in individuals. Telomere length is a reflection of how quickly or slowly a person’s cells are aging, making it a key indicator for scientists studying the potential impact of caloric restriction on aging in humans.
“There are numerous factors that could contribute to the potential extension of human lifespans through caloric restriction, and this is an area that is still undergoing active research,” said Waylon Hastings, a member of the research team.”Dr. Smith earned his doctorate in biobehavioral health from Penn State in 2020 and was the main author of this research. The primary way that life is prolonged is related to the metabolic process within a cell. When a cell uses energy, byproducts of that process can lead to oxidative stress, which can harm DNA and cause the cell to deteriorate. However, when a person’s cells consume less energy due to caloric restriction, there are fewer byproducts, and the cell does not break down as quickly.”
The scientists examined the telomere length of 175 participants in the CALERIE study at the beginning, one year into the study, and theThe study concluded after 24 months of caloric restriction. Around two-thirds of the participants were involved in caloric restriction, while the remaining one-third served as the control group. The results of the study revealed that the trajectory of telomere loss changed during the study. In the first year, participants who restricted their caloric intake lost weight and experienced a faster rate of telomere loss compared to the control group. However, after a year, the weight of the participants on caloric restriction stabilized, and the restriction continued for another year. In the second year, the participants on caloric restriction experienced a slower rate of telomere loss than before.
After two years, the control group and the group on caloric restriction had similar telomere lengths, indicating no statistically significant difference between the two groups.
“This study highlights the complexities of how caloric restriction impacts telomere loss,” Shalev explained. “Our initial hypothesis was that telomere loss would be slower in individuals on caloric restriction. However, our findings revealed that those on caloric restriction experienced a more rapid telomere loss at first, followed by a slower rate after their weight stabilized.”
Shalev emphasized that these results raise important questions, such as the potential impact on telomere length if Data had been gathered for an additional year? Participants in the study are set to have their data collected at a 10-year follow-up, and Shalev expressed his anticipation to analyze that data once it is available.
Even though the results are unclear, Shalev mentioned that there is potential for positive health effects from caloric restriction in humans. Previous research on the CALERIE data has indicated that caloric restriction may help lower harmful cholesterol levels and reduce blood pressure. The two-year timeframe for telomeres was not enough to demonstrate benefits, but Shalev and Hastings believe they may still be revealed.
Three of Shalev’s trainees, Hastings, current graduate student Qiaofeng Ye and former postdoctoral scholar Sarah Wolf, led the research under Shalev’s guidance.
Hastings said that being able to lead this study was crucial for his career.
“I was recently hired as an assistant professor in the Department of Nutrition at Texas A&M University, and I will begin that work in the fall semester,” Hastings said. “Prior to this project, I had limited experience in nutrition. This project truly shaped the direction of my career, and I am appreciative to Dr. Shalev for entrusting me with that responsibility.”
Calen Ryan and Daniel Belsky of Columbia UniversThe research was a collaboration between several institutions including Columbia University Mailman School of Public Health, Tufts University, Duke University School of Medicine, University of British Columbia, Pennington Biomedical Research Center, and Arizona State University College of Health Solutions. The National Institute on Aging provided the funding for this research.
