Data from the European Prospective Investigation into Cancer and Nutrition (EPIC) showed that for every 200 grams (about two servings) of total fruits and vegetables eaten per day, the incidence of cancer was reduced by 4 per cent.
The new study, published in the Journal of the National Cancer Institute, is the largest on diet and cancer to date, and included 142,605 men and 335,873 women. The participants were followed for an average of about nine years, during which time over 30,000 cases of cancer were diagnosed.
Taking heart from the science
Experts from across the globe have been quick to note, however, that the results do not undermine recommendations for eating at least five servings of fruit and vegetables a day, with studies reporting cardiovascular benefits.
In an accompanying editorial, Prof Walter Willett from the Harvard School of Public Health noted that one study reported no link between cancer and fruit and vegetable intake, but a 30 per cent lower risk of coronary heart disease or stroke.
“[Also,] data from a large randomized trial showing that increasing intake of fruits and vegetables reduces blood pressure, a major determinant of cardiovascular disease, make the case for causality compelling, although benefits through additional pathways are also possible,” wrote Willett.
“Thus, recommendations and actions to increase intake of fruits and vegetables have a sound basis,” he added.
Door not closed
Prof Willett also noted that the weak link between fruit and vegetables and overall cancer risk should “not exclude the possibility that one or a small group of fruits or vegetables, or a specific substance in some of these foods, has an important protective effect”.
Indeed, Prof Willett notes that a considerable body of science supports an apparently link between lycopene and tomato products and a reduced risk of prostate cancer.
“Furthermore, multiple lines of evidence indicate that ionizing radiation and some other risk factors for cancer can operate primarily in childhood and early adult life; thus, antioxidants or other protective constituents of fruits and vegetables may need to be present at that time to be effective,” wrote Prof Willett.
“Like the European Prospective Investigation into Cancer and Nutrition (EPIC), almost all studies of diet and cancer would have missed such effects because they started decades later in life,” he added.
Commenting independently on the research, Yinka Ebo, health information officer at British charity Cancer Research UK, said: “It’s still a good idea to eat your five-a-day but remember that fruits and vegetables are pieces in a much larger lifestyle jigsaw.
“There are many things we can do to lower our chances of developing cancer such as not smoking, keeping a healthy weight, cutting down on alcohol, eating a healthy balanced diet, being physically active and staying safe in the sun.”
Source: Journal of the National Cancer Institute
Published online ahead of print, doi:10.1093/jnci/djq072
“Fruit and Vegetable Intake and Overall Cancer Risk in the European Prospective Investigation Into Cancer and Nutrition (EPIC)”
Authors: P. Boffetta, E. Couto, J. Wichmann, P. Ferrari, et al.
Editorial: Journal of the National Cancer Institute
10.1093/jnci/djq098
“Fruits, Vegetables, and Cancer Prevention: Turmoil in the Produce Section”
Authors: W.C. Willett