New research from a University College London (UCL) team has concluded that seven or more portions of fruit and vegetables gives people a much greater chance of avoiding an early death.
The study published on Tuesday even suggests that the government's current 5-a-day recommendation should be doubled to 10.
Experts at UCL studied 65,226 men and women and found that eating seven portions of fruit and veg a day reduced a person's risk of dying from heart disease by 31 percent and of cancer by 25 percent.
The research also found that people who ate seven or more portions daily had a 42 per cent reduced risk of death overall compared to those who managed just one.
In a controversial finding, researchers say frozen and tinned fruit increases the risk of premature death by 17 percent - due to the high amount of sugar contained within.
Currently, one in four Britons manages to eat 5-a-day.
"We all know that eating fruit and vegetables is healthy, but the size of the effect is staggering," said lead author Dr Oyinlola Oyebode of UCL's Department of Epidemiology and Public Health.
"The clear message here is that the more fruit and vegetables you eat, the less likely you are to die at any age.
Vegetables have a larger effect than fruit, but fruit still makes a real difference. If you're happy to snack on carrots or other vegetables, then that is a great choice but if you fancy something sweeter, a banana or any fruit will also do you good.
"However, people shouldn't feel daunted by a big target like seven. Whatever your starting point, it is always worth eating more fruit and vegetables. In our study even those eating one to three portions had a significantly lower risk than those eating less than one."
The study is calling for the 5-a-day message based on World Health Organisation guidance to be revised while also possibly excluding dried and tinned fruit, smoothies and fruit juice which also contain large amounts of sugar.
On the other hand many say it is too soon to change a public health message that is widely understood and that changing the goal to 7-a-day will stop people from trying to eat a healthier diet altogether.