What would you do for an extended period of golden years? Most of us pinch pennies, but few of us diet. After all, what’s the point of that epic retirement cruise if you can’t overindulge?
A new study by scientists from the US and China suggests that if you want to reduce levels of inflammation throughout your body, delay the onset of age-related diseases and live longer, you should eat less food.
This is the result of the most detailed report to date of the cellular effects of a calorie-restricted diet in rats – while the benefits of caloric restriction have long been known, this new study shows how restriction can protect against aging in cellular pathways.
As detailed in scientific journal Cell on February 27, 2020, “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 Juan Carlos Izpisua Belmonte, a senior author of the new paper, professor in Salk’s Gene Expression Laboratory and holder of the Roger Guillemin Chair. “This gives us targets that we may eventually be able to act on with drugs to treat aging in humans.”
But first, some background. As Science Daily reports, “Aging is the highest risk factor for many human diseases, including cancer, dementia, diabetes and metabolic syndrome.” Meanwhile, “caloric restriction has been shown in animal models to be one of the most effective interventions against these age-related diseases.”
And, up until now, although researchers knew that individual cells undergo many changes as an organism ages, they have not known how caloric restriction might influence these changes.
In the new paper, Belmonte and his collaborators compared rats who ate 30 percent fewer calories with rats on normal diets. The rats’ diets were controlled from age 18 months to 27 months (in humans, this equates to following a calorie-restricted diet from about age 50 through 70).
At both the start and finish of the diet, Belmonte’s team isolated and analyzed a total of 168,703 cells from 40 cell types in the 56 rats. These cells came from fat tissues, liver, kidney, aorta, skin, bone marrow, brain and muscle.
“In each isolated cell, the researchers used single-cell genetic-sequencing technology to measure the activity levels of genes. They also looked at the overall composition of cell types within any given tissue. Then, they compared old and young mice on each diet,” Science Daily reports.
“Many of the changes that occurred as rats on the normal diet grew older didn’t occur in rats on a restricted diet; even in old age, many of the tissues and cells of animals on the diet closely resembled those of young rats. Overall, 57 percent 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,” Science Daily.
“This approach not only told us the effect of calorie restriction on these cell types, but also provided the most complete and detailed study of what happens at a single-cell level during aging,” says co-corresponding author Guang-Hui Liu, a professor at the Chinese Academy of Sciences.
Some of the cells most affected by the diet related to inflammation. In fact the number of immune cells in nearly every tissue studied significantly increased as control rats aged but was not affected by age 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” says co-corresponding author Jing Qu, also a professor at the Chinese Academy of Sciences.
“People say that ‘you are what you eat,’ and we’re finding that to be true in lots of ways,” added Concepcion Rodriguez Esteban, another of the paper’s authors and a staff researcher at Salk. “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 team is now trying to use this information to discover aging drug targets and implement strategies towards increasing life and healthspan.
Until then, continue with your doughnuts…