You've probably seen some headlines in recent years heralding the correlation between a lowered caloric intake and increased lifespan. The topic has been a rich area of research for decades, but scientists have been unable to successfully explain the phenomenon. New research from a team at Temple University may have finally cracked the puzzle by revealing that epigenetic changes that occur with age can be slowed through a calorie-restricted diet.

The research focused on the process of DNA methylation, a chemical activity that essentially directs when a gene should or shouldn't be expressed. These methylation patterns were found to shift as an animal ages, increasing and decreasing in different genomic areas.

"Our study shows that epigenetic drift, which is characterized by gains and losses in DNA methylation in the genome over time, occurs more rapidly in mice than in monkeys and more rapidly in monkeys than in humans," says senior investigator Jean-Pierre Issa.

Using deep-sequencing technology the team first studied how age-related variations in DNA methylation were correlated with an animal's lifespan. It was discovered that the greater the epigenetic change from methylation, the shorter the animal's lifespan.

Knowing that a great deal of research has already shown how calorie restriction can increase lifespan, the focus of the study then moved on to examining whether reduced dietary calories had a direct effect on epigenetic drift.

Groups of rhesus monkeys and mice fed calorie restricted diets both displayed reduced evidence of epigenetic drift when compared to similar control groups eating an average caloric volume. The rhesus monkeys, eating a diet with 30 percent less calories than normal, displayed a blood methylation age equivalent to animals seven years younger.

The results were even more pronounced in the mice studies, which the researchers suggest is related to the animal's shortened lifespan (allowing for a restricted diet to be imposed over the animal's entire life), and the increased restriction of the diet (which was increased to a 40 percent caloric reduction).

"The impacts of calorie restriction on lifespan have been known for decades, but thanks to modern quantitative techniques, we are able to show for the first time a striking slowing down of epigenetic drift as lifespan increases," says Issa.

As well as offering a key insight into how a caloric restricted diet could increase a person's lifespan, the research highlights how modifying the body's natural epigenetic drift process could have significant impacts on preventing age-related diseases.

Questions over what causes this epigenetic drift to occur more rapidly in some people over others are now primary areas of investigation for the researchers, with the next step to begin examining what other factors could impact on this process.

The study was published in the journal Nature Communications.