We all know the cliche "an apple a day keeps the doctor away," but in recent years, many studies have taken that promise even further, linking the daily consumption of fruits and vegetables to a reduced risk of mortality—especially from heart disease and cancer.
In a review and analysis of such studies published in The BMJ, researchers from China and the U.S. found that indeed, consuming fruits and vegetables is correlated with a lower risk of death in some cases—but that the association is not consistent for all types of death.
The researchers looked at 16 studies, which included a total of 833,234 participants, 56,423 of whom died. In order to minimize bias, investigators took into account various differences in study design and quality, and analyzed subgroups to confirm that results did not vary significantly by location.
Consuming more fruits and vegetables was significantly associated with a reduced risk of death from most causes. The average risk of death from all causes was lowered by 5 percent for each additional daily serving of fruit and vegetables, and the risk for cardiovascular death was reduced by 4 percent.
Interestingly, researchers found that once you reach five portions of fruits and vegetables per day, more of the healthy foods will not further reduce the risk of death.
This contradicts another recent study published in The BMJ's Journal of Epidemiology and Community Health that suggested seven or more daily portions of fruits and vegetables were linked to lowest risk of death. However, researchers said studies may differ in their classifications of fruits and vegetables, and there was room for error in how people reported their eating habits on surveys used.
Eating more fruits and vegetables was not appreciably associated with risk of death from cancer, according to the study. Researchers said more studies are needed to examine specific types of cancer and the role of different groups of fruit and vegetables.