Eating fruits and vegetables may lower the risk of cancer, particularly cancers of the gastrointestinal tract, according to a high-level international review of research findings. The scientific review, coordinated by the WHOs International Agency of Research on Cancer (IARC), was carried out by a Working Group of 22 scientists, from 10 countries.
At a week-long meeting in Lyon, France, the group concluded that findings from both human studies and animal experimental studies "indicate that a higher intake of fruits and vegetables is associated with a lower risk of various types of cancer."
The clearest evidence of a cancer-protective effect of eating more fruits is for stomach, lung and oesophageal cancers. Similarly, in the teams words, "a higher intake of vegetables probably reduces the incidence of cancers of the oesophagus and colon-rectum."
"In many studies, there is a fairly consistent association of higher levels of fruits and vegetables intake with some reduction in cancer risk," said Professor Paul Kleihues, Director of the IARC. "This, plus the evidence of beneficial effects of fruits and vegetables on other major diseases such as heart disease, indicates that individuals and communities should increase their intake of these foods. This is an important message for governments, the food industry and consumers."
The Working Group estimated that approximately one in ten cancers in western populations are due to an insufficient intake of fruits and vegetables. Similar, although variable, fractions apply to other populations around the world, and may be higher in regions where the intake of fruits and vegetables is lower.
The Working Groups chairman, Professor Tony McMichael, from the Australian National University, pointed out that the evidence for any particular type of cancer in relation to fruits and vegetables intake lacks certainty. However, the pattern of findings for cancers overall is persuasive, he said.
"Individual dietary habits are complex," said Professor McMichael, "and they are accompanied by various other personal behaviours, such as smoking and alcohol consumption, that can also affect cancer risk. So, it is not easy to get conclusive evidence on diet-cancer relationships." However, long-term follow-up studies of many thousands of persons from the general population are now providing higher-quality information about these relationships, he said.