You’ve heard it a thousand times, that little catchphrase with the magic number encouraging you to eat “five a day” of fruits and vegetables for better health. But it turns out that the real magic number is eight, according to a new comprehensive study just published in the International Journal of Epidemiology.

The study, spearheaded by Dagfinn Aune from NTNU and Imperial College London, shows that 7.8 million deaths worldwide could be prevented each year if people ate more fruits and vegetables. Aune says the more you eat, the lower the overall risk of heart disease, stroke, cancer and premature death.

“The results support recommendations to increase the amount of fruits and vegetables people eat,” said Aune.

The study shows that the risk of dying prematurely from all causes was reduced by almost a third, and the risk of cardiovascular disease by about a quarter in people who ate 800 grams of fruit and vegetables every day, compared with those who ate very little or no fruits and vegetables.

“We see a gradual reduction in risk with increasing consumption, so a low or moderate intake is better than not eating fruits and vegetables at all,” he said.

It should be no surprise to anyone that eating fruits and vegetables is linked to better health, but none of the previous analyses that have established this link have examined how much you should eat to increase health benefits.

The meta–analysis undertaken by Aune and his colleagues is by far the largest on this topic to date. The researchers looked at a total of 142 publications from 95 different population studies that studied the relationship between consumption of fruits and vegetables and the subsequent risk of chronic diseases. Each analysis included information on several hundred thousand people.

“The risk of heart disease, strokes and premature death decreased by 10.8 per cent for each 200 gram increase in consumption of fruit or vegetables – up to an intake of 800 grams,” Aune said.

He stressed that the greatest impact from increasing a person’s daily intake of fruit and vegetables appears to be in people do not eat fruit and vegetables at all, or who eat very little of them. But there were also benefits from additional increases in fruit and vegetable consumption for people whose diets already include some fruit and vegetables.

Many national health authorities recommend that people eat at least “five a day,” which corresponds to approximately 500 grams of fruit and vegetables. In other words, the new analysis suggests that the risk of disease and premature death can be reduced even more by eating more fruits and vegetables than recommended.

The researchers also calculated how many premature deaths that could be prevented each year worldwide, if everyone ate 800 grams of fruit and vegetables every day. The figure they arrived at was 7.8 million deaths each year. If everyone ate 500 grams a day, that figure would be 5.4 million deaths.

Two to four million deaths related to cardiovascular disease could be prevented a year if everyone ate optimal amounts of fruits and vegetables, the researchers said, while for cancer that number was approximately 660,000 deaths.