Want to live longer? The secret to a long life lies in restricting intake of calories, a new study has found. Eating less, or restricting intake of calories, reduces levels of inflammation throughout body, delays the onset of age-related diseases and increases survival.
This new study, published in the journal Cell, brings us one step closer to living a long life, by elucidating the underlying mechanisms. Researchers have found that ageing causes a functional decline in tissues throughout the body that may be delayed by caloric restriction.
For years, science has shown that restricting the number of calories ingested, while maintaining overall nutrition, is a health-promoting habit. “We already knew that calorie restriction increases life span, but now we’ve shown all the changes that occur at a single-cell level to cause that,” said Dr Juan Carlos Izpisua Belmonte, a senior author of the study.
For the study, researchers recorded and analysed the effects of caloric restriction on individual cells in rats. They considered 56 rats that were put on a diet with 30% fewer calories, compared to standard rat diets, from the age of 18 months to 27 months. In terms of human age, this corresponds to the period between 50 years and 70 years.
They extracted almost 170,000 cells of 40 different types, from the rats, in two stages - at the beginning of the study and at its end. These cells came from fat tissues, liver, kidney, aorta, skin, bone marrow, brain and muscle. In each of the cells that was taken from the animals, the genes were sequenced so that the impact of the dietary restriction on their expression levels could be identified. The scientists also examined the overall composition of the cell types found in any type of tissue before and after the experiment. Finally, they made a comparison of the changes in old and young mice on the standard versus calorie-restricted diet.
They found that there were many changes occurring with age in the rats on a standard diet that failed to make their appearance in the cells taken from rats on calorie-restricted diet. In fact, the tissues and cells in the old rats fed a calorie restricted diet were very similar to those from the younger rats. There was an overall reduction of 57% in the age-related changes in the cell composition in rats on a calorie-restricted diet.
The cells and tissues that were turned down low included those that regulate immune function, inflammation and fat metabolism. In almost all the tissues, there was a markedly increased number of immune cells with age which was absent in the calorie restricted rats. Especially in the metabolically active type of fat called brown fat, calorie restriction suppressed gene expression related to inflammatory activity, to the level more typical of young rats. This means that age-related inflammation can be regulated by this lifestyle modification.
“People say that ‘you are what you eat’, and we’re finding that to be true in lots of ways,” says Dr Concepcion Rodriguez Esteban, another of the paper’s authors and a staff researcher at Salk’s Gene Expression Laboratory. “The state of your cells as you age clearly depends on your interactions with your environment, which includes what and how much you eat.”
The research team is now trying to utilise this information to discover ageing drug targets and implement strategies towards increasing life and health span.
