Diet and cancer risk in Mediterranean countries: open issues.

OBJECTIVE: To analyse various aspects of the Mediterranean diet in relation to the risk of several common cancers in Italy.
DESIGN: Data from a series of case-control studies conducted in northern Italy between 1983 and 2004 on over 20,000 cases of several major cancers and 18,000 controls.
RESULTS: For most digestive tract cancers, the risk decreased with increasing vegetable and fruit consumption, with relative risks between 0.3 and 0.7 for the highest level of intake, and the population-attributable risks for low intake of vegetables and fruit ranged between 15 and 40%. Less strong inverse relations were observed for other (epithelial) cancers, too. A number of micronutrients contained in vegetables and fruit showed an inverse relation with cancer risk. In particular, flavones, flavonols and resveratrol were inversely related to breast cancer risk. Olive oil, which is a typical aspect of the Mediterranean diet, has also been inversely related to cancers of the colorectum and breast, and mainly of the upper digestive and respiratory tract. Consumption of pizza, one of the most typical Italian foods, was related to a reduced risk of digestive tract cancers, although pizza may simply be an aspecific indicator of the Italian diet.
CONCLUSIONS: Adherence to the Mediterranean diet is a favourable indicator of the risk of several common epithelial cancers in Italy. A score summarising the major characteristics of the Mediterranean diet was related to a priori defined reduced risks of several digestive tract neoplasms by over 50%.