The BBC reports that those who at seven servings of fruit and especially vegetables a day extended their lives by 40%.
Eating seven or more portions of fruit and vegetables a day is healthier than the minimum five currently recommended and would prolong lives, experts say.
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.
Risk of death by any cause over the course of the study was reduced by 42% for seven or more portions of fruit and veg (up to around 10 portions a day).
Fresh vegetables had the strongest protective effect, followed by salad and then fruit.
Fruit juice conferred no benefit, while canned fruit appeared to increase the risk of death – possibly because it is stored in sugary syrup, say the researchers.
Lead investigator Dr Oyinlola Oyebode said: “The clear message here is that the more fruit and vegetables you eat, the less likely you are to die – at any age.”
She said the size of the effect was “staggering”, but added that eating a few portions a day was still better than nothing.