Slowing down the ageing process may be as simple as cutting calories by 25 per cent, scientists have found.
Although the recommended calorie intake for women is 2,000 and 2,500 for men, knocking consumption down by a quarter appears to bring significant health benefits, and may stave off an early death.
Scientists at Columbia University, in New York, carried out a randomised control trial of 220 healthy adults, half of whom were asked to cut their calories, while the rest stuck to traditional healthy eating guidelines.
Researchers found that the speed of ageing was two to three per cent slower for people on a calorie-restricted diet, which would translate to a 10 to 15 per cent decrease in the risk of early death.
The benefit is similar to the effect of someone giving up smoking.
“Our findings are important because they provide evidence from a randomised trial that slowing human ageing may be possible,” said Dr Calen Ryan, a Research Scientist at Columbia’s Butler Aging Center and co-lead author of the study.
A calorie-restricted diet involves reducing daily intake below what’s recommended, but still maintaining good nutrition and essential vitamins and minerals.
Previous studies have shown that cutting calorie intake could slow down the biological ageing process, and extend healthy lifespan in worms, flies and mice.
In the study involving worms, a fasting diet increased lifespan by 40 per cent, while in monkeys calorie restriction reduced the incidence of age-related conditions, such as cancer, heart disease, and diabetes.
There is also evidence that calorie restriction can improve outcomes for obese people, but the new trial is the first to show beneficial ageing effects for healthy humans.
Monitoring ageing in short-lived animals is easy, but it would take decades to see similar changes in humans. Instead, scientists rely on biomarkers which can measure the pace of biological ageing over a shorter study period.
The rate they were ageing was monitored by looking at blood DNA. Over time, DNA acquires tiny chemical modifications – known as methyl groups – which can change how genes work.
The accumulation of such methyl groups can be used as a clock to measure ageing, with more DNA modifications suggesting faster ageing.
Researchers also found that the majority of participants were not able to stick to the 25 per cent reduction, with most opting for 20 per cent – suggesting that the benefit still works, even with less restriction.
A follow-up of trial participants is now ongoing to determine if the intervention had long-term effects on healthy ageing. Previous studies have shown that a slower ageing rate reduces the risk of heart disease, disability, strike and dementia.
“Our study of the legacy effects of the intervention will test if the short-term effects observed during the trial translated into longer-term reduction in ageing-related chronic diseases or their risk factors,” says Dr Sai Krupa Das, a senior scientist and investigator who is leading the long-term follow up of participants.
Commenting on the research, Naveed Sattar, Professor of Metabolic Medicine at the University of Glasgow, said: “This seems well done research on complex markers in the context of a small scale calorie reduction trial, but do we really need to prove that eating less calories slows ageing processes?
“This should be evident from national data sets that show people from Japan who remain leaner than most are amongst the longest living of any nation.
“This new work fits with an emerging body of evidence all pointing in the same direction.”
Lower blood pressure
Previously, the same study was carried out on obese people, and calorie restriction was found to lower blood pressure and reduce cholesterol which could be expected to decrease the risk of diabetes, heart disease and stroke.
Experts are still unsure why calorie restriction brings ageing benefits but believe it may reduce inflammation, improve sugar metabolism, and maintain cellular function and DNA. It may also help reduce oxidative stress which can damage cells and tissues.
However, some people on calorie-restricted diets have reported side effects in the past, such as a loss of bone density, muscle mass and aerobic capacity.
The research was published in the journal Nature Ageing.
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