A large body of evidence indicates that high intakes of fruit and vegetables are associated with a reduced risk of
cancer at several sites. The association is generally most marked for epithelial
cancers, apparently stronger for those of the digestive and respiratory tracts, and somewhat weaker for
hormone-related
cancers. The relationship between frequency of consumption of vegetables and fruit and
cancer risk was analysed using data from a series of case-control studies conducted in northern Italy since 1983. The relative risks (RRs) for most common
neoplasms ranged from 0.2 to 0.5 for the highest compared with the lowest tertile of vegetable intake. Protective effects were highest for
epithelial neoplasms, but were also observed for
hormone-related
neoplasms. Fruit was related to reduced RRs for
cancers of the oral cavity and pharynx, oesophagus, stomach, larynx, as well as of the urinary tract. There was a specific and consistent pattern of protection by tomatoes, a typical Mediterranean food, with RRs between 0.4 and 0.7, most notably for
gastrointestinal neoplasms. No significant association was observed between fruit and vegetable consumption and non-epithelial lymphoid
neoplasms. For digestive tract
cancer, population attributable risks for low intake of fresh vegetables and fruit ranged from 15 to 40% of all cases in this Mediterranean population. Combined with tobacco and alcohol, the population attributable risks exceeded 85% for men and 55% for women for upper digestive and
respiratory tract neoplasms. Thus, from a public health viewpoint, epidemiological evidence indicates that a substantial reduction in epithelial
cancer risk can be obtained by increasing fruit and vegetable consumption.