Eating seven or more portions of fruit and vegetables a day is healthier than the five currently recommended and would prolong lives, researchers say.
A study of 65,226 men and women indicated the more fruit and vegetables people ate, the less likely they were to die - at any given age.
Seven a day cut the risk of dying from cancer and heart disease.
But the government says its "five-a-day" advice is sufficient and that many of us struggle to achieve even this.
Experts said other lifestyle factors, such as not smoking or drinking excessively, may have accounted for the drop in mortality, not just fruit and veg consumption, although the study authors said they had tried to account for this.
The University College London researchers used the National Health Survey, which collects data from people in England each year through questionnaires and nurse visits, to look at diet and lifestyle.
They analysed data between 2001 and 2008, which provided a snapshot rather than people's continuing dietary habits.
The study looked at general mortality as well as death from cancer, heart disease and stroke, and found risk of premature death from any cause decreased as fruit and veg consumption increased.