Unraveling the link between calorie restriction and telomeres

New research looks at the impact of calorie restriction on telomere length, shedding light on the complex relationship between diet and aging.

The role played by diet – when, how and what we eat – has been of keen interest for geroscience researchers. Calorie restriction, in particular, has come under the spotlight due to its potential to seemingly slow down the aging process and extend lifespan. Now, a new study from Penn State University has explored into the intricate mechanisms behind calorie restriction, focusing on its effect on telomeres — the protective caps at the ends of chromosomes that are implicated in cellular aging.

Longevity.Technology: For years, researchers have explored the idea that reducing calorie intake could be a key to extending lifespan; studies in animals have consistently shown that calorie restriction can lead to longer lifespans and better healthspans, but translating these findings to humans has proven to be more challenging, although the recent CALERIE clinical trial found that people who eat a calorie restricted diet can slow their pace of aging by 2% to 3% compared with people on a normal diet – a slow down that could equate to a 10% to 15% reduction in the likelihood of dying early [1]. Now a deeper analysis of the CALERIE data is helping to shed light on the reasons for that lifespan extension.

A recent study led by Dr Idan Shalev and his team at Penn State aimed to unravel some of the mysteries surrounding caloric restriction and its effects on aging. The researchers analyzed data from the CALERIE study, a landmark clinical trial that investigated the impact of calorie restriction on various health outcomes in humans to ascertain if this calorie reduced diet had an effect on telomeres, a biological marker of cellular aging [2].

Telomeres play a crucial role in maintaining the stability of our chromosomes. With each cell division, telomeres gradually shorten, eventually reaching a point where the cell can no longer replicate. This phenomenon, known as the Hayflick limit, is a fundamental aspect of cellular aging. Shortened telomeres are associated with a range of age-related diseases and conditions, and telomere length reflects how quickly or slowly a person’s cells are aging – this makes them a key target for longevity research.

“There are many reasons why caloric restriction may extend human lifespans, and the topic is still being studied,” said Waylon Hastings, lead author of this study. “One primary mechanism through which life is extended relates to metabolism in a cell. When energy is consumed within a cell, waste products from that process cause oxidative stress that can damage DNA and otherwise break down the cell. When a person’s cells consume less energy due to caloric restriction, however, there are fewer waste products, and the cell does not break down as quickly [3].”

The findings of the Penn State study, published in Aging Cell, offer new insights into how caloric restriction influences telomere length and, by extension, the aging process. Examining data from 175 participants of the two-year study, the researchers found that participants who restricted their calorie intake experienced changes in telomere length that differed from those in the control group. Initially, telomeres in the calorie-restricted group shortened more rapidly than those in the control group. However, as the study progressed, the rate of telomere loss in the calorie-restricted group slowed down, eventually reaching a point where there was no significant difference in telomere length between the two groups [2].

“This research shows the complexity of how caloric restriction affects telomere loss,” Shalev said. “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 [3].”

The Penn State study suggests that the relationship between calorie restriction and aging is complex and may depend on factors such as the duration and intensity of the restriction. The participants in the study are due for another data collection at a 10-year follow-up, and Shalev said that he was eager to analyze those data when they become available.

Despite the ambiguity of the results, Shalev remains optimistic about the potential health benefits of caloric restriction. Previous research from the CALERIE study has shown that calorie restriction can lead to improvements in cholesterol levels and blood pressure, suggesting that it may have broader implications for health and aging [4]. However, further research is needed to fully understand the mechanisms underlying these effects and to determine the optimal strategies for promoting healthy aging in humans.

While the study from Penn State represents an important step forward in our understanding of how diet impacts aging, when it comes to telomeres, the two-year timeline was not long enough to demonstrate benefit – but watch this space for the ten-year study, as those benefits, says Shalev, by still be revealed.

[1] https://www.nature.com/articles/s43587-022-00357-y
[2] https://onlinelibrary.wiley.com/doi/10.1111/acel.14149
[3] https://www.psu.edu/news/health-and-human-development/story/calorie-restriction-study-reveals-complexities-how-diet-impacts/
[4] https://pubmed.ncbi.nlm.nih.gov/31303390/