Restricting food-calorie intake may help reduce levels of inflammation throughout the body, delay the onset of age-related diseases, and increase lifespan, according to a study which provides the most detailed report to date of the cellular effects of a calorie-restricted diet in rats.
While the benefits of caloric restriction have been widely studied, the new results, published in the journal Cell, showed how it protects against ageing by shedding light on the chemical processes happening at the cell-level under the diet.
How Caloric Restriction might Influence Age-related Diseases
Caloric restriction has been shown in animal models to be one of the most effective interventions against age-related diseases like cancer, dementia, and diabetes.
Although scientists know that individual cells undergo many changes as an organism ages, they have not known how caloric restriction might influence these changes.
Current research compared rats which ate 30 per cent fewer calories with those on normal diets. The research found the animals’ diets were controlled from age 18 months through 27 months. Researchers isolated and analysed a total of 1,68,703 cells from 40 cell types in the 56 rats at both the start and the conclusion of the diet. These cells came from fat tissues, liver, kidney, aorta, skin, bone marrow, brain and muscle.
The researchers then used single-cell genetic-sequencing technology to measure the activity levels of different genes in each of these cells. They also assessed the overall composition of cell types within the tissues, and also compared old and young mice on each diet.
According to the study, many of the changes that occurred as rats on the normal diet grew older didn’t occur in the rodents on a restricted diet.
The scientists said even in old age, many of the tissues and cells of animals on the diet closely resembled those of young rats. About 57 per cent of the age-related changes in cell composition seen in the tissues of rats on a normal diet were not present in the rats on the calorie restricted diet.
Immunity, Inflammation and Fat Metabolism Most Affected by Calory-Intake
Some of the cells and genes most affected by the diet were related to immunity, inflammation, and fat metabolism. According to the scientists, the number of immune cells in nearly every tissue studied dramatically increased as control rats aged, but was not affected by age in rats with restricted calories.
They said in brown adipose tissue — one type of fat tissue — a calorie-restricted diet reverted the expression levels of many anti-inflammatory genes to those seen in young animals.
The primary discovery in the current study is that the increase in the inflammatory response during ageing could be systematically repressed by caloric restriction.