HOW DOES CALORIC RESTRICTION PROLONG LIFE?
Calorie restriction is one of the recurring subjects of some nutritionists and in the specialized press, such as sequential fasting (fasting once a week from 8 pm until one day at 1 pm).
This is no coincidence, since the caloric restriction has real effects. Especially in the case of cancer, it would modify the expression of genes involved in the development of the disease and could thus increase the effectiveness of certain anti-tumor treatments.
This “technique” of restricting calories consists of eating a little less calories on a daily basis than our real need and would have effects on longevity. Moreover, the caloric restriction perfectly illustrates what my grandmother (or yours maybe) often said to me: ” Jimmy! Do not get out of a full table! ” . She overcame the malnutrition of two wars and a heart attack, and lived in good shape until the age of 93!
However, even if this technique has been recognized as beneficial for a long time, its mechanism – which operates a long life – has just been revealed in the results of a study published on September 14, 2017.
THE CALORIE RESTRICTION TO LIVE OLDER?
Almost a century ago, scientists discovered that reducing caloric intake could dramatically prolong the life of some animal species. Despite numerous studies carried out since then, the researchers could not explain precisely why.
Now, researchers from the Lewis Katz School of Medicine at the American University of Philadelphia (LKSOM) have overcome this barrier. In the new works published online in the scientific journal Nature Communications , they are the first to demonstrate that the rate at which the epigenome (the epigenetic changes of a cell and the epigenetic state of the cell) changes with age associated with the life span of species and that caloric restriction slows down this process of change – potentially explaining its effects on longevity.
SLOW DOWN EPIGENETIC DRIFT TO CONTROL LONGEVITY
This 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.
The results explain why mice live only about two to three years on average, rhesus monkeys (rhesus monkeys) of about 25 years and humans of 70 or 80 years.
Chemical modifications such as DNA methylation control mammalian genes, which serve as bookmarks for the use of a gene – a phenomenon known as epigenetics. Methylation patterns drift consistently throughout life, with methylation increasing in some regions of the genome and decreasing in others. Previous studies have shown that these changes occur with age, but if they were also related to lifespan, this was totally unknown.
The slowing down of epigenetic drift
The team of researchers made its discovery after examining patterns of methylation on DNA in the blood collected from individuals of different ages for each of the three species – mouse, monkey and human. Mice ranged from a few months to almost three years, monkeys less than one year to 30 years old and humans aged 0 to 86 years (cord blood was used to represent age zero).
Age-related changes in DNA methylation were analyzed using a high-performance sequencing method, which revealed distinct models with methylation gains in elderly individuals occurring in genomic sites that did not, were not methylated in young people and vice versa.
In the following analyzes, striking losses in gene expression were observed in genomic regions that were increasingly methylated with age, whereas regions that had become less methylated showed an increase in expression of Genoa.
The Benefits of Tea in Women
The study of a subset of genes affected by changes related to the age of methylation revealed an inverse relationship between methylation drift and longevity. In other words, the greater the amount of epigenetic change, the longer it has occurred, the shorter the lifetime of the species.
The researchers wanted to know if the epigenetic drift could be modified in order to increase the lifetime. One of the strongest known factors to increase lifespan in animals is the calorie restriction, in which diet calories are reduced while retaining the supply of essential nutrients.
To examine its effects, researchers reduced caloric intake by 40% in young mice and 30% in middle-aged monkeys. In both species, significant reductions in epigenetic drift were observed, so that age-related changes in elderly animals in calorie-restricted diets were comparable to those in young animals.
EPIGENETIC DRIFT IS A DETERMINANT OF LIFETIME IN MAMMALS
With these new findings, researchers are able to propose a new mechanism – the slowing down of epigenetic drift – to explain how caloric restriction prolongs life in animals.
The impacts of calorie restriction on life expectancy have been known for decades, but thanks to modern quantitative techniques, researchers can show for the first time a slowing down of epigenetic drift as the life span increases.
Finally, the findings have important implications for health research, where recent studies have suggested that a greater amount of epigenetic drift increases the risk of age-related diseases, including cancer.
The research laboratory proposing this latter study was the first to propose the idea of modifying the epigenetic drift as a means of modifying the risk of disease.
However, the reason why epigenetic drift occurs more rapidly in some people and slower in others is still uncertain.
The research team hopes to quickly identify other factors that influence the drift of methylation. Such factors could potentially be altered to slow drift, with major impacts on the prevention of age-related diseases.
On the other hand, the restriction is not practiced in any way, since it weakens us and has other repercussions. In this way, it is necessary to speak to your doctor or nutritionist, in order to advise you on a personalized diet, and to open a therapeutic window for this restriction according to your state of health.