Vegetables, fruit, antioxidants and cancer: a review of Italian studies.

BACKGROUND: Case-control studies have suggested that a diet rich in fresh fruit and vegetables protects from the risk of most common epithelial cancers, including those of the digestive tract, and also several nondigestive neoplasms; however, selections in cohort studies have been generally weaker. AIM OF THE STUDY: To review the relation between frequency of consumption of vegetables and fruit, estimated intake of selected antioxidants and the risk of cancer at different sites.
METHODS: Systematic overview of data, with specific focus on a network of case-control studies conducted in Italy from 1983 to 1999.
RESULTS: The relative risks (RR) of digestive tract neoplasms were reduced in subjects reporting highest vegetable intake. A protective effect of vegetables was also observed for hormone-related neoplasms. Fruit was related to a reduced RR of cancers of the upper digestive tract, stomach and urinary tract. With reference to the role of selected antioxidants, beta-carotene, vitamins C and E showed a significant inverse relation with oral and pharyngeal, esophageal and breast cancer risk. Against colorectal cancer, the most consistent protective effects were provided by carotene, riboflavin and vitamin C, but inverse relations were observed also for calcium and vitamin D.
CONCLUSIONS: Fruit and vegetable consumption in Mediterranean populations appears to provide protection against several types of neoplasms.