Telomeres: How Diet Impacts Aging

Telomeres are like protective caps at the end of our chromosomes. However, every time cells replicate the telomeres get shorter, and the genetic information they once protected can become damaged, preventing future reproduction or proper cell function, and throughout human life can eventually result in replicative cell senescence or apoptosis. 

Telomeres are the focus of a great deal of anti-aging, regenerative, and longevity research because cells with longer telomeres are functionally younger than those with shorter telomeres; meaning that people of the same chronological age can have different biological ages depending on the length of their telomeres. 

How often our cells replicate and how much length that telomeres retain can be influenced by typical aging, illness, stress, genetics, diet, and much more. This study investigated the effects of caloric restriction on telomere length in humans because telomere length indicates how quickly or slowly our cells are aging, examining their length could help to identify a way to slow aging. 

"There are many reasons why caloric restriction may extend human lifespans, and the topic is still being studied," said Waylon Hastings, who earned his doctorate in biobehavioral health at Penn State in 2020 and was 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."

Telomere length was monitored for 175 participants (two-thirds participated in caloric restriction and the other third served as a control group) using data from the start of the CALERIE Study, one year into the study, and at the end of the study after 2 years of caloric restriction. The analysis revealed that telomere loss changed trajectories over the study period. Over the first year, those in the restricting group lost weight as well as telomeres more rapidly than those in the control group. After the first year, weight loss was stabilized in the restricting group. During the second year, those in the restricting group lost telomeres more slowly than those in the control group. However, after two years, the lengths of the telomeres among the two groups were not statistically different. 

Prior research on the CALERIE data showed that caloric restriction may help to reduce levels of harmful cholesterol and lower blood pressure. However, for telomeres, the two-year timeline was not sufficient enough to show benefits, but those benefits may still be revealed as the participants are scheduled for a 10-year follow-up to see what happens to telomere length at a longer duration. 

"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."