Dietary non-nutritive cancer protective factors

It has been widely believed that the majority of cancers in humans were caused by exposure to environmental carcinogens. The pronounced variation in incidence rates of specific cancers from one country to another was explained by a variation in the load of carcinogens to which people were exposed from the sea of carcinogens in which they lived. This native and simple point of view can no longer be upheld. It is becoming evident that this theory cannot quantitatively explain the observed occurrence of cancer. Variations in the intake of compounds with anticarcinogenic effects might just as well be made responsible for a major part of the variation in cancer incidence. A review is given of this emerging field and it is argued that the study of anticarcinogens may allow us to reach a more balanced concept of the causative network in human cancer. It should also equip us with better means for more effective cancer prevention.