A balanced diet that provides all the nutrients our body needs, but with fewer calories, is one of the most effective measures to avoid excess weight and its adverse consequences, such as obesity and diabetes, but it can also help prevent or delay some of the diseases associated with aging.
New research has proven, in fact, that reducing total calorie intake can boost muscle strength, even though muscle mass is lost with age, and contribute to healthy aging. The study was carried out by researchers from the National Institutes of Health (NIH) of the United States and their colleagues.
In animal models, it had already been proven that reducing the number of calories consumed while still providing the body with essential vitamins and minerals – known as calorie restriction – delays the progression of diseases associated with aging. The new work has been published in Aging Cell and suggests that the same biological mechanisms can apply in humans.
A slight reduction in calories had good results
To carry out the study, data were analyzed from people who had participated in the Comprehensive Long-Term Effects Evaluation of Energy Reduction (CALERIE), a study supported by the National Institute on Aging (NIA) that evaluated whether restriction Moderate calories provide the same health benefits that have been observed in animal studies.
“Given that inflammation and aging are strongly linked, calorie restriction represents a powerful approach to prevent the pro-inflammatory state that many older people develop”
Over a two-year period, the goal for participants was to reduce their daily caloric intake by 25%, but the group was only able to achieve a reduction of 12% at most. However, this slight decrease in calories was enough to activate most of the biological pathways that are important for healthy aging.
“A 12% reduction in calorie intake is very modest,” said Dr. Luigi Ferrucci, corresponding author and chief scientific officer at NIA. And he adds that “this kind of small reduction in calorie intake is doable and can make a big difference in your health.”
The researchers sought to understand the molecular underpinnings of the benefits seen in previous research on calorie restriction in humans. One study showed that individuals who restricted their calorie intake lost muscle mass and an average of 20 pounds during the first year and maintained their weight for the second year. However, despite losing muscle mass, calorie-restricted participants did not lose muscle strength, indicating that calorie restriction improved the amount of force generated by each unit of muscle mass, called muscle-specific force.
To conduct the new study, scientists used thigh muscle biopsies from CALERIE participants, which were collected when the individuals joined the study, and at one-year and two-year follow-ups. To find out which human genes were affected by calorie restriction, scientists isolated messenger RNA (mRNA) – a molecule that contains the code for proteins – from muscle samples.
They determined the protein sequence of each mRNA and used this information to identify the genes that gave rise to specific mRNAs. Further analyzes helped the researchers establish which genes were up-regulated during calorie restriction, meaning the cells made more mRNA, and which were down-regulated, meaning the cells made less mRNA.
The researchers confirmed that calorie restriction affected the same genetic pathways in humans as it did in mice and non-human primates. For example, lower caloric absorption up-regulated genes responsible for energy generation and metabolism, and down-regulated inflammatory genes leading to less inflammation. “Given that inflammation and aging are strongly linked, calorie restriction represents a powerful approach to prevent the pro-inflammatory state that many older people develop,” concludes Ferrucci.
