We have reached the conclusion that what we eat is responsible for a large number of tumors, and that certain foods trigger cancer while others have … - Umberto Veronesi

A vegetarian diet, by reason of its low content of saturated fatty acids, cholesterol, and animal proteins, and its high concentrations of folic acids, antioxidants, and phytoestrogens—shown to be effective in inhibiting the growth or in promoting the regression of serious coronary pathologies—constitutes a barrier against a number of chronic degenerative diseases, cancer among them. And that is not all. Fruits and vegetables—besides contaminating us much less than some other foods—are troves of precious substances that enable the neutralization of carcinogenic agents and that 'dilute' the concentration of diseased cells and reduce their proliferation. All of these advantages, as well as many others, emerged from studies on populations in the last century.

It should be remembered that the pharmacologic treatment of raised farm animals can cause damage to the health of anyone who eats their meat. For example, the antibiotics that are legally added to animal feed—with the objective of preventing infections—can cause a resistance to antibiotics in humans. That is to say, a selection of bacterial strains resistant to antibiotics can be transmitted from animals to man through food; and can thereby generate infections difficult to stop (at times fatal, as with salmonella).

Fruit and vegetables, instead, are foods extremely low in fats and high in fiber: by easing the passage of ingested food, they reduce the time of contact between possible carcinogens—present in our daily diet—with the walls of the intestines.