“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,” says Salk professor Juan Carlos Izpisua Belmonte.

Belmonte and his team compared rats that ate 30% fewer calories – from 18 months through 27 months – with rats on normal diets; in humans, this would be roughly equivalent to someone following a calorie-restricted diet from 50 years through 70 years.

Even as they aged, many of the tissues and cells of rats on the diet closely resembled those of young rats, with 57% of the age-related changes in cell composition seen in the tissues of rats on a normal diet absent in the rats on the calorie-restricted diet. (The scientists used single-cell genetic-sequencing technology to measure the activity levels of genes in cells from the rats’ fat tissues, liver, kidney, aorta, skin, bone marrow, brain and muscle.)

Most surprising was that cells and genes related to immunity, inflammation and lipid metabolism were greatly affected by the calorie-restricted diet.In brown adipose tissue, a calorie-restricted diet seemed to reverse the expression levels of many anti-inflammatory genes to those seen in young rats – in fact, the number of immune cells in nearly every tissue studied dramatically increased as control rats aged, but was not affected by aging in rats with restricted calories.

“The primary discovery in the current study is that the increase in the inflammatory response during aging could be systematically repressed by caloric restriction” said Jing Qu, a professor at CAS.

The team is now trying to utilise the information gleaned in an effort to discover aging drug targets and implement strategies towards increasing life and health span.

Staff researcher at Salk, Concepcion Rodriguez Esteban, summarises, “People say that ‘you are what you eat,’ and we’re finding that to be true – the state of your cells as you age clearly depends on your interactions with your environment, which includes what and how much you eat.”