The research, which involved a 12-year study, also found that vegetables were four times healthier than fruit.

The study, by University College London, found that eating large quantities of fruit and vegetables significantly lowered the risk of premature death. People who ate at least seven portions of fruit and vegetables each day were 42 per cent less likely to die from any cause over the course of the study.

The researchers also discovered that canned and frozen fruit increased the risk of dying by 17 per cent, and fruit juice was found to have no significant benefit.

The findings suggest that the five-a-day recommendation, suggested by the World Health Organisation and backed by the Government and NHS, is not adequate - although only 30 per cent of people manage to eat that amount.

Experts said that even seven-a-day was not enough and that 10 would be the optimum number, as the protective effect continued to increase with higher consumption.

The study’s lead author, Dr Oyinlola Oyebode of UCL’s department of epidemiology and public health, said: ‘‘The clear message here is that the more fruit and vegetables you eat, the less likely you are to die at any age. My advice would be, however much you are eating now, eat more.’’

Health experts called on the Government to subsidise the cost of fruit and vegetables, which they suggested could be paid for by taxing sugary foods.

The five-a-day guidelines were based on World Health Organisation recommendations issued in 1990, which advised consuming 400g of fruit and vegetables each day to lower the risk of heart disease, stroke, type-two diabetes and obesity.

Prof Simon Capewell, of the department of public health at the University of Liverpool, said the advice should be 10 portions a day. ‘‘Humans are designed to be omnivorous: a handful of nuts, seeds, fruit and the occasional antelope. We’re not meant to be eating junk food.’’

Researchers examined the eating habits of 65,000 people in England between 2001 and 2013.

They found that seven helpings a day of fruit or vegetables could reduce a person’s overall risk of premature death by 42 per cent when compared with people who ate just one whole portion. 

People who ate between five and seven portions a day had a 36 per cent reduced risk of death, those who ate three to five portions had a 29 per cent decreased risk and those who ate one to three helpings had a 14 per cent reduced risk.

Those with the highest intakes were also 25 per cent less likely to die from cancer and 31 per cent less likely to die from heart disease.

“This is exciting research in cancer prevention," said Australian Cancer Council Nutrition Program Manager, Clare Hughes.

"We know that eating the right amount of fruit and vegetables has a protective effect, but this large scale research shows the more fruit and veg that are consumed, the better chance you have of preventing cancer,”

Current Health Statistics show 51% of adults in NSW consume the right amount of fruit, while just 9% eat five serves of vegetables.

‘‘We need to urgently examine seriously the proposal to increase recommended intake to seven a day,’’ said Naveed Sattar, professor of metabolic medicine at the University of Glasgow.

‘‘To implement a seven-a-day message would be really challenging for many in society and would require governmental support such as subsidising the cost of fruit and vegetables, perhaps by taxing sugar-rich foods.’’

The study also found that vegetables were far more beneficial than fruit. Each portion of vegetables lowered the risk of death by 16 per cent. However, each piece of fruit only lowered the chance of death by 4 per cent.

The authors said the findings lent support to the Australian government’s advice of ‘‘two plus five’’ a day, which encourages people to eat two helpings of fruit and five of vegetables. Dr Alison Tedstone, the group’s director of diet and obesity, said: ‘‘Our focus remains on increasing overall consumption of fruit and vegetables to meet current recommendations.’’

The study was published in the Journal of Epidemiology and Community Health.

The Telegraph, London