How an apple a day really can help keep ageing away

The fruit contains a particularly beneficial flavanol called quercetin, and just 10mg reduces the odds of frailty by 20pc, according to a study.

Up to 15pc of older adults experience frailty, a geriatric syndrome that leads to a greater risk of falls, fractures, disability, hospital admissions, and death.

Current dietary recommendations for frailty prevention primarily focus on protein intake, but experts said it was becoming clear that certain fruits were also helpful for lowering the risk.

Flavanols are found in many foods including green leafy vegetables, apples, lettuce, tea, onions, berries, blackcurrants, cherries, peaches, soybeans, citrus foods, chocolate, peppers, grapes and even wine.

“Higher flavonols intake was associated with lower odds of developing frailty,” said Professor Shivani Sahni of Harvard Medical School.

“Specifically, higher quercetin intake was the flavonoid that had the strongest association with frailty prevention.

“This data suggests that there may be particular subclasses of flavonoids that have the most potential as a dietary strategy for frailty prevention.”

Flavanols help to regulate cellular activity and work as antioxidants to fight off free radicals that cause oxidative stress and damage in the body.

The research was based on data from volunteers in the Framingham Heart Study which has monitored the health of residents of Framingham, Massachusetts, since the 1940s. A total of 1,701 over-65s took part in the study which resulted in 13.2pc of participants becoming frail by the end of the 12-year project.

Those who had the highest flavanols intake – particularly quercetin – were found to be the least likely to become frail.

There is mounting evidence that flavanol may also be useful in fighting Alzheimer’s disease, cancer, cardiovascular disease, arthritis, high blood pressure and Type 2 diabetes.

Research by Wageningen University in the Netherlands also found that eating an average-sized apple would reduce the risk of stroke by between 36-45pc, because of quercetin.

A University of Reading study found that eating two apples a day lowered levels of “bad” cholesterol by almost 4pc. “There may be some validity to the old saying, an apple a day keeps the doctor (or frailty) away,” researchers concluded in the study published in the American Journal of Clinical Nutrition.